RPR is still missing texture nodes for musgrave, voronoi, sine/saw waves, bricks, as well as a distortion modifier for the noise node. This makes the use of procedural textures essentially impossible at the moment.
This has been requested many times before but I also want to chime in that a solid setup of noises, functions, and mappings would be very useful and something one have come to expect that from a renderer these days. Especially important that noises are 4d (x,y,z, time) and that that texure mapping can be easily modified with translation, scale, rotation. Need to work with volumes as well for allowing classics like turbulent fogs, clouds etc.