| rif | FRAMES Receptor Intakes File |
| riff | Resource Interchange File Format |
| rinex | Receiver Independent Exchange Format Data |
| rio | OMICRON Test Universe RIO Object |
| rir | RIR Statistics Exchange Format Data |
| rit | DriveClone Data File |
| riv | CRiSP Harvest Data |
| rjt | RealJukebox Track Info Style |
| rki | Race-Keeper Video Index Data |
| rkl | VST-AU Alpha JUNO Editor License Key Data |
| rkn | Reckon Personal Plus Backup Data |
| rkp | RemoteKeys Profile Data |
| rkplr | NI REAKTOR Player Data |
| rky | SDLX Registration Key Data |
| rld | RecLoad Definition |
| rlg | RegCleaner Language File |
| rlhead | CrazyTalk Head Data |
| rlist | PLINK Rare Genotype List File |
| rlo | Reflection Desktop Layout Data |
| rlog | MPICH Log Data |
| rlt | ReliaSoft Weibull++ Template |
| rlw | ReliaSoft Weibull++ Page |
| rlx | XMetaL Author Rules Data |
| rly | Railway Operation Simulator Layout Data |
| rm2 | Hammer Reminders Data |
| rm2db | ReefMaster Workspace |
| rm3d | RiskMetrics RiskManager Data |
| rm7 | Casio WK-6500 Registration Memory Data |
| rma | Rhapsody DRM License Data |
| rmat | EUHEDRAL Reciprocal Axes Matrix Data |
| rmb | RegistryMaster Data |
| rmbak | Registry Mechanic Backup |
| rmc | RMCalc Data |
| rmdb | ReefMaster Workspace |
| rmdu | RemoteMaster Device Upgrade |