The trouble with "bitness" (aka architecture) and shiming.

TIMOTHY_MANGAN The PSF Launcher executable comes in both 32 and 64 bit variants, both of them being able to launch any kind of process as long as the PSF Runtime dll with the same bitness as the launched process is also present in the package with a corresponding name (PsfRuntime.dll or PsfRuntime[arch].dll).

Another PSF component available is PsfRunDll executable which is needed only if the main application process creates additional processes (with different bitness), so I would say that the bitness issues are being handled automatically by the PSF.

If you are using a tool with PSF support, like Advanced Installer, all that bootstrapping is being done behind the scenes, you just have to pick the predefined fixup you need since all are available for both architectures.