Hi @Michaelkm8,
Unfortunately, we can no longer assist with converting ProSource 8 files to the RSMX format. As of OpticStudio 23.2, the RSMX Libraries and all of its associated features have officially been deprecated. As such, we no longer have the capability to work with ProSource8 files. You can read more about this change in our Community Notes for that release: OpticStudio 23.2 Release Notes | Zemax Community.
My recommendation is to reach out to the vendor that is supplying the source files. If they have Prosource 8 files on their website, it is possible they would be able to assist with converting the files to a different format.