To properly execute your Codicil, you must sign it in the presence of your chosen witnesses. Your witnesses should not be listed as beneficiaries in your Last Will.
It is best practice to initial at the bottom of each page, except the signing page of your Codicil, which requires your full signature. No text should appear on the last page after your signature, not including the witness signing area.
Most states only require you to have two witnesses. After you have signed and initialed your document in front of witnesses, your witnesses must initial each page and sign the final page of the Codicil. Their signing must occur in your presence. Your witnesses may have to appear before a court to verify that this process was completed and that you were of age and sound mind at the time.