| 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 |
| rmed | Salome-Meca Exported MED Results Data |
| rmf | Adobe Acrobat Rights Management File |
| rmg | RootsMagic v1 Database |
| rmgb | RootsMagic v4 Database Backup |
| rmgc | RootsMagic v4 Database |
| rmir | RemoteMaster IR Setup |
| rmk | Remark Office OMR Remark Data |
| 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 |
| rnk | GSEA Ranked List File |
| rnk | GOLD Rank 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 |