Verification Process for Tank Busting Claims

[Boomerang]

I am seeking information about what process (if any) was used to verify the tank busting claims by the likes of Hans-Ulrich Rudel. Was there a formal process for claims to be submitted to the RLM for approval, such as applied for claims by fighters? If not, were the tallies of tank kills, such as the 519 claimed by Rudel, kept at unit level, or by individual pilots?

Also, I'd be interested in comments on the reliability, or otherwise, of tank busting claims.

Thanks

Boomerang