"Do you know if it does the reverse (converting rsr to png)?" No, it can't do it, but for what do you need to convert rsr to png?, Poser 5/6 understand rsr. It's not difficult to do it, but it is useless. I have restricted the conversion to only sizes of 91x91 pixels, the program can handle any size, but Poser4 do not!

Stupidity also evolves!