It's easy to make the .rsr thumbnail. Just save your character with the materials you want - we'll say Vic-White in this case. Create your MAT file and save it in the RuntimelibrariesPose[whatever folder] Go to the runtimelibrariescharacter[whatever folder] and copy the Vic-White.rsr file. Go to the RuntimelibrariesPose[whatever folder] where you saved your MAT file and make sure it has the same name as your new MAT file. Ta Da! Instant thumbnail. If you want to get fancy with the .rsr, I have a tutorial on that which I think it pretty easy to follow. I also have a tutorial on zipping things up to make it easier for people to download and install. Cheers!