It is still in your introduction,
http://www.tweaksoftware.com/products/rv-packages
But I can't found it in preferences setting or any where in rv installed directory.
The release notes of 3.12.13 just say you update but not remove it, right?
I use rv 3.12.19, 3.12.20 on windows 7 and ubuntu 12.04
playlist-1.2.rvpkg