RoHS certificate is a self-declaration letter. You can declare the compliance after checking for ROHS chemicals. The following steps are to be followed for RoHS certification. a. Testing: Through XRF testing and/or lab phthalate solvent extraction testing to be done to determine values of the ten restricted RoHS substances. b. Process Audit: Inspect all applicable manufacturing processes used towards RoHS compliance on-site. c. Documentation Review: Review the Bill of Materials, assembly drawings, materials declarations, test reports, and conformance/compliance certificates from all suppliers. d. Certification Statement: After a successful audit, a RoHS Certificate of Compliance (also known as a Certificate of Conformity or Declaration of Conformity) can be issued.