| rmuf | Alpha Five Runtime Users Data |
| rnc | RELAX NG Compact Syntax |
| rng | RELAX NG Syntax File |
| rnw | Sweave Document |
| robo | RoboMind Source Code |
| rodl | RemObjects Definition Language |
| ron | Ron Document |
| rotest | RemObjects SDK Test Data |
| rotestresult | RemObjects SDK Test Results Data |
| rpd | RapidPLUS Application File |
| rpf | ProWorx NXT Cross-reference Pointer |
| rplib | Axure RP Widget Library |
| rpo | GCC Compiler Template Object |
| rpp | FactoryTalk View Studio RecipePlus Component File |
| rpp | RPP Script |
| rpp | SymbianOS Pre-processed Resource |
| rpy | RenPy Script |
| rpyb | RenPy Bytecode |
| rpyc | RenPy Compiled Script |
| rpym | RenPy Module |
| rpymc | RenPy Module |
| rqc | Micro Focus Revolve Compiled Script |
| rqs | Micro Focus Revolve Script |
| rr2 | Radare2 Debug Profile Data |
| rrc | BlackBerry Resource Content |
| rrh | BlackBerry Resource Header |
| rsc | Pegasus Mail Compiled Resource |
| rsg | SymbianOS Resource Header |
| rsi | Reactis Info File |
| rsl | Robot Scripting Language |
| rsnippet | Rsnippet Data |
| rsp | MSBuild Response File |
| rsrc | Mac OS X Resource Data |
| rsrs | Buddy API Data |
| rt | Apache Jena RDF Thrift Data |