I've been using the R4DS from the start, but since they released the firmware with the themes file, i cannot get a skin to work. It just keeps reverting back to the beta skin. I've tried placing the skin in the root of the SD card. In the '_system_' folder. In the 'Themes' within the '_system_' folder...and nothing works.
Assuming you haven't done this, you need to replace the original skin files in "_system_\themes\theme01" with your own. Then boot the R4 and press Select to load your theme.
If you've tried that and you still have trouble, then you can use chishm's
r4crypt (yasu's is supposed to be more refined, but I have no experience with it and can't find a link quickly) along with case's
injektor to overwrite the default skin built into the firmware.