| rmskin | Rainmeter Skin |
| rmt | Netgear Router Firmware |
| rmtl | Rhino 3D Material Data |
| rmw | RAM Commander Database |
| rmx | Remark Office OMR Remark Data |
| rmz | Microsoft Outlook Exported Rules Data |
| rnan | Nitro Animation Resource |
| rnd | General Random Seed File |
| rnh | SPANS Raster Header Data |
| rnk | GOLD Rank Data |
| rnk | GSEA Ranked List File |
| rnl | SPANS Raster Interchange Data |
| rno | PDP-10 Runoff Input Data |
| rnt | EdgeCAM Licensing Data |
| rnx | RealPlayer RNX Data |
| roc | SpaceCAD Rocket Model |
| roca | RIB Office Compressed Archive |
| rod | Siebel Report Object Design |
| rodx | Ancestry Genealogical Database |
| rodz | Ancestry Genealogical Database |
| rog | Roger 2 Input Data |
| roh | Avantes USB Spectrometer Data |
| roi | MotionTracking Regions of Interest Data |
| roi | Siebel Report Object Instance |
| roi | Shark ROI System Data |
| rok | Roku HD1000 Firmware Update |
| rol | Siebel Report Object Library |
| rom | General ROM Image |
| rom | AMI BIOS Firmware Update |
| rom | NES ROM Image |
