There are spaces in a single RIShader operation to assign up to 6 different RenderMan shaders to 6 (possibly different) groups of primitives. If that is not adequate then users can string a sequence of RIShader operations together to assign more than 6 different shaders. Note that you can override a shader assignment within a sequence of RIShader operations.
Specify the groups in question
Name of RenderMan Shader to assign to the said group(s)