Note that this question is about the programming language RPL for the Commodore PET, not the HP language with the same name. RPL was developed by Tim Stryker and sold through his company Samurai Software at least as early as 1981, together with some other development and debugging tools. RPL is a stack oriented language, like Forth, and compiles to byte code. The manual can be found here.
I only recently learned about this language and like its clever balance between simplicity, speed, and compact code. However, it does not seem to have been very popular. The only materials that I can find online (e.g. on archive.org) are either generic reviews of RPL, or articles written by Tim Stryker himself.
So my question: Was RPL for the Commodore PET ever seriously used, other than in projects involving Tim Stryker himself? I’d be very interested in any references.