Guide
Open a Reaper Project in Autodesk Flame
Flame can import an OMF file's audio, which is what the converter makes from your Reaper project.
In Flame's Clip Library menu, choose OMF as the Interchange Format and click Import, then select the .omf file and click Load. Select the events that reference audio and click Import to bring the audio into the clip library.
Audio embedded in the OMF is extracted into a new folder named after the file. Flame reads WAV and AIFF-C audio at 44.1 or 48 kHz, so keep your Reaper project's audio at one of those rates.
You can convert your Reaper project to OMF for free here.
Going the other way? Here's how to open an OMF file in Reaper.