I never figured out how scaling works for imported obj files in Poser, it's very confusing... But: If you supply it as a pp2 file, Poser users will not need the obj file at all. The geometry is embedded in the pp2. People will just load your prop from the Props library and the scaling will be as you intended. No need to include the obj file in your package unless you want users of other applications to use the armchair as well.