| Abbreviation | Definition |
|---|---|
| RDF | Reasons, Details, Facts |
| RFMTS | Radio Frequency Microphone Telephone Surveillance |
| RGPO | Rendezvous Guidance and Procedures Office |
| RH | Richmond Field Office |
| RI | Reserve Index |
| RKS | Record Keeping System |
| RM | Racial Matter |
| RM | Registered Mail |
| ROCIC | Regional Organized Crime Information Center |
| RT | Rucni Top |
| RTAL | Road Transportable Analytical Laboratory |
| RTM | Really Twisted Mind |
| RUC | Referred Upon Completion |
| RWBS | Report Will be Submitted |
| SA | San Antonio Field Office |
| SAB | Security Advisory Board |
| SAC | Special Agent in Charge |
| SACB | Subversive Activities Control Board |
| SAotG | Spying Agencies of the Government |
| SARAA | South Area Regional Abduction Alert |