| rcl | Reflection Command Language Script |
| rcn | QRacing Track Records Data |
| rco | PlayStation Portable Resource Data |
| rcq | RESTClient Requests File |
| rcr | SAP Business One XL Reporter Data |
| rctd | RabbitCT Dataset |
| rcut | Webinaria Recording Cut |
| rcw | RaceSail Regatta Data File |
| rd | Reaction Data File |
| rd1 | DATAIR Retirement Plan Document System Data |
| rd3f | Ray Dream 3D Data |
| rd3x | Reflection Desktop Session Data |
| rd4a | Ray Dream 3D v4 Animation |
| rd5x | Reflection Desktop Session Data |
| rda | Oracle Database Storage Area |
| rda | Siemens MR Spectroscopy ASCII Data |
| rdat | RNA Data |
| rdb | Oracle Database Root |
| rdbx | RiScan Pro Point Cloud Data |
| rdc | CYANA Residual Dipolar Coupling Restraint File |
| rdd | IBM Informix Genero Studio Data Schema |
| rdf | Reaction Data File |
| rdh | Siemens MR Spectroscopy Header Data |
| rdi | SPEFO Differential Spectrum Data |
| rdic | StarDict Dictionary Resource |
| rdj | JCanyon Texture Data |
| rdml | Real-time PCR Data Markup Language Data |
| rdo | Oracle Database Redo Log |
| rdox | Reflection Desktop Session Data |
| rdr | Dynamic Report Decoder File |
| rdx | Borland Reflex Data File |
| rdy | Ready Pro Accounting Data |
| rdy | TSP-INet Server Acknowledge Data |
| rdz | RemoteDocs Encrypted Document |
| re1 | Hy-Tek Meet Manager Registration Data |