When you book your appointment, many/most consulate send you a list of exactly what forms and supporting documents they require. Eg, some consulates have a short local questionnaire in addition to, or in place of, the 4079.
Forms for Renunciation
4079. Request for determination of possible loss of US citizenship. Important for reliquishments, is not strictly required for renunciations (according to the DOS procedure manual) but it some consulates use it.
4080. Oath of renunciation
Statement: NOT required. People generally do not write one.
Forms for Relinquishment
If you have already relinquished your citizenship (eg. upon obtaining citizenship in another country, government employment, etc.) and are now applying for a CLN:
Statement. NOT required. But can be useful to supplement your 4079 with a written statement to show that your relinquishment was intentional and that your post-relinquishment conduct has been consistent with having relinquished. Some people do, some don’t.
Department of State Procedure Manuals
7 FAM 1210: Introduction
7 FAM 1220: Developing a Loss-of-Nationality Case
7 FAM 1260: Renunciation of US Citizenship
7 FAM 1270: Military Service and Loss of Nationality
1200 Appendix A: Loss of Nationality and the Early Years of the Republic
1200 Appendix B: US Supreme Court Decisions on Loss of Nationality
1200 Appendix D: Fradulent Naturalization
(There does not appear to be an “Appendix F,” at least not on the internet at this time.)
1200 Appendix G: Posthumous Loss of Nationality
Department of State Overseas Citizens Services E-mail inquiries
Links to US Embassies and Consulate Websites
Department of State Telephone Directory