As SteveJax said, the best way to distribute a figure is in a cr2 (character) file, not in a pz3 (scene) file.

In your original post, you give examples of a relitive path such as:

RunTime:Geometries:artist:product:product_lowpoly.obj

Perhaps that was just a typographic error in your post, but that syntax is wrong and would not work. The path statement needs to start with a colon (:), so the path should read:

:Runtime:Geometries:artist:product:product_lowpoly.obj

Also, the use of a capitalized "T" in "Runtime" is something I have never seen before. It's possible that this is something that has changed since my version of Poser (P6), and the paths may not be case sensitive in any case, but it's something that may be worth checking.