RenderMan for Houdini (RfH) only provides support for the following production Houdini versions:

• RenderMan for Houdini 26.0 supports: 20.0.653, 19.5.805, 19.0.720

Other important information:

• Minimum USD version is 22.05 so RenderMan in Solaris operates in >= 19.5.
• RenderMan for Houdini on Linux will only operate with the gcc9.3 houdini build.
• RenderMan for Houdini will not operate with a mismatched python version. Be careful to install the same python version for Houdini and RfH. 
• Rendering with RenderMan will not operate on Houdini Apprentice editions, see Side FX's website for options that allow Third Party Rendering
• RenderMan for Houdini for 19.0 requires macOS 12.x Monterey and higher or CentOS 7.7 - 7.9.