There are a few procedures in the PERC manual which produce RDBs; the procedures describe the RDBs as being in DRC or ERC format. It also provides instructions on opening them in Calibre RVE. More commonly, only the PERC report is produced. You can still use YieldServer to generate an RDB.
The format of both ERC and DRC RDB files is documented in the Calibre Verification User's Manual, under "ASCII DRC Results Database Format."