I’m not sure how to add new shaders to retroarch. There’s no default shader in there dealing with curature, so I wanted to try out GRT-Geom for example. Do I simply download the shader from

http://filthypants.blogspot.se/2012/07/customizing-cgwgs-crt-pixel-shader.html

and place it in the retroarch/shader directory?

Sorry for being a complete n00b.