Poser 4 makes an RSR the first time you load an item - thereafter it uses the RSR if it exists, which is faster. So if you modify the OBJ file, Poser will continue to load the RSR and will miss your modification. This would be a problem only if you altered the OBJ file after opening the item in Poser 4. The RSR will be in the Geometries folder where the OBJ is located, with the same file name root.