I looked at some guides but I am unable to access the RA shader directory to add shaders to RA (sonkun, etc). Is there a guide on how to add these shaders and where the location to add is? It seems hidden for some reason. Thanks.
I had this issue yesterday too, and I what I did was set a custom directory to store shaders, re-download the shaders and use that directory to load custom shaders.
Right now, my shaders are stored on the sdcard/retroarch/shaders directory in my SD card (alongside my saves and save states)