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| Delaware                                                      | 20-4077773                          |
|---------------------------------------------------------------|-------------------------------------|
| (State or other jurisdiction ofincorporation or organization) | (I.R.S. EmployerIdentification No.) |

| Large accelerated filer                                            | o | Accelerated filer         | o |
|--------------------------------------------------------------------|---|---------------------------|---|
| Non-accelerated filer(Do not check if a smaller reporting company) | o | Smaller reporting company | x |

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|   | PART IV |
|--------|---------|

| ITEM 15. | EXHIBITS, FINANCIAL STATEMENT SCHEDULES |
|----------|-----------------------------------------|

| EXHIBIT |   |                                                                                                                                                                                                                                                    |   |                                    |
|---------|--------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|-----------------------------------------|
| NUMBER  |   | TITLE OF EXHIBIT                                                                                                                                                                                                                                        |   | METHOD OF FILING                        |
|    |   |                                                                                                                                                                                                                                                    |   |                                    |
| 3.1     |   | Articles of Formation of Ridgewood Energy S Fund, LLC                                                                                                                                                                                                   |   | Incorporated by reference to the Fund's |
|    |   | filed with the Secretary of State of the State of Delaware                                                                                                                                                                                              |   | Form 10 filed on April 24, 2007         |
|    |   | on December 19, 2005                                                                                                                                                                                                                                    |   |                                    |
|    |   |                                                                                                                                                                                                                                                    |   |                                    |
| 3.2     |   | Limited Liability Company Agreement between Ridgewood Energy                                                                                                                                                                                            |   | Incorporated by reference to the Fund's |
|    |   | Corporation and Investors of Ridgewood Energy S Fund, LLC                                                                                                                                                                                               |   | Form 10 filed on April 24, 2007         |
|    |   | dated February 1, 2006                                                                                                                                                                                                                                  |   |                                    |
|    |   |                                                                                                                                                                                                                                                    |   |                                    |
| 31.1    |   | Certification of Robert E. Swanson, Chief Executive Officer of the Fund,                                                                                                                                                                                |   | Filed herewith                          |
|    |   | pursuant to Securities Exchange Act Rule 13a-14(a)                                                                                                                                                                                                      |   |                                    |
|    |   |                                                                                                                                                                                                                                                    |   |                                    |
| 31.2    |   | Certification of Kathleen P. McSherry, Chief Financial Officer of the Fund,                                                                                                                                                                             |   | Filed herewith                          |
|    |   | pursuant to Securities Exchange Act Rule 13a-14(a)                                                                                                                                                                                                      |   |                                    |
|    |   |                                                                                                                                                                                                                                                    |   |                                    |
| 32      |   | Certifications pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of The Sarbanes-Oxley Act of 2002, signed by Robert E. Swanson, Chief Executive Officer of the Fund and Kathleen P. McSherry, Chief Financial Officer of the Fund |   | Filed herewith                          |
|    |   |                                                                                                                                                                                                                                                    |   |                                    |
| 99      |   | Report of Ryder Scott Company, L.P.                                                                                                                                                                                                                     |   | Filed herewith                          |

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|                   | RIDGEWOOD ENERGY S FUND, LLC |
|------------------------|------------------------------|
|                   |                         |
|                   |                         |
| Date: August 23 , 2010 | By:                          | /s/ ROBERT E. SWANSON |
|                   |                         | Robert E. Swanson |
|                   |                         | Chief Executive Officer |
|                   |                         | (Principal Executive Officer) |

| Signature                    | Capacity                                                                                   | Date                   |
|------------------------------|--------------------------------------------------------------------------------------------|------------------------|
|                         |                                                                                       |                   |
| /s/ ROBERT E. SWANSON        | Chief Executive Officer                                                                    | Date: August 23 , 2010 |
| Robert E. Swanson            |          (Principal Executive Officer)        |                   |
|                         |                                                                                       |                   |
|                         |                                                                                       |                   |
| /s/ KATHLEEN P. MCSHERRY     | Executive Vice President and Chief Financial   Officer (Principal Accounting Officer) | Date: August 23 , 2010 |
| Kathleen P. McSherry         |                                                                                       |
|                         |                                                                                       |                   |
| RIDGEWOOD ENERGY CORPORATION |                                                                                       |
| /s/ ROBERT E. SWANSON        | Chief Executive Officer of Manager                                                         | Date: August 23 , 2010 |
| Robert E. Swanson            |                                                                                       |                   |
|                         |                                                                                       |                   |

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