I don't see any reference to the .sfz format but you can import your own samples. You can read about importing user multi-samples starting on page 54 of the manual. Seems like a pretty comprehensive tool:
https://parawave-audio.com/public-downl ... Manual.pdf
I haven't tried it yet but I've got a bunch of samples made for Zampler that I might try importing. The only difference will be the .sfz file itself (unless I'm wrong about .sfz file import in Rapid).
The factory samples are in a proprietary .pws format