Many federal courts require the parties to utilize CM/ECF (case management / electronic court filing system) to file documents, including proofs of service. If you file a document electronically, you won't need to worry about things like bluebacking. Look into this. Also, you need to be familar with (1) Federal Rules of Civil Procedure, (2) Rules of the Central District Court of California, and (3) Rules or Standing Orders of your judge. You will find quite a bit of information in the Central District website.
This response is for information purpose only and does not constitute a legal advice. This response does not create an attorney-client relationship.
Yes, the proof of service needs to be filed with the U.S. District Court for the Central District of California.
I agree with Attorney Lee. The days of bluebacking are over, now that the court expects all documents to be electronically filed.
The information presented here is general in nature and is not intended, nor should be construed, as legal advice. This posting does not create any attorney-client relationship with the author (who is only admitted to practice law in the State of California). For specific advice about your particular situation, consult your own attorney.