| rr2 | Radare2 Debug Profile Data |
| rrc | BlackBerry Resource Content |
| rrh | BlackBerry Resource Header |
| rs | Rust Source Code |
| rsc | Pegasus Mail Compiled Resource |
| rsdk | Retro-Engine SDK Data |
| rsg | SymbianOS Resource Header |
| rsi | Reactis Info File |
| rsl | Robot Scripting Language |
| rslib | ABB RobotStudio Library |
| rsnippet | Rsnippet Data |
| rsp | MSBuild Response File |
| rspag | ABB RobotStudio Pack and Go Archive |
| rsrc | Mac OS X Resource Data |
| rsrs | Buddy API Data |
| rsstn | ABB RobotStudio Station Data |
| rt | Apache Jena RDF Thrift Data |
| rte | Crestron SIMPL Route Data |
| rtw | Real-Time Workshop File |
| ruby | Ruby Console Application |
| ruf | ProWorx NXT Address Used Tables Reference |
| rul | InstallShield Install Script |
| rule | Visual C++ Project Rules |
| rules | Visual C++ Project Rules |
| rur | RUR-PLE Solution |
| rvb | Rhino 3D Visual Basic Script |
| rvf | RichView Format Data |
| rvi | Crestron RoomView Information Data |
| rvo | ER/Studio Comparison Quick Launch Data |
| rvr | RapidPLUS Reviewer Application |
| rvt | VersaPro Reference View Table |
| rwplugin | RapidWeaver Plugin |
| rwsnippet | RapidWeaver Snippet File |
| rwstyle | RapidWeaver Style File |
| rwtheme | RapidWeaver Theme File |
