There are three new RiProcedures implemented for the RIS mode of PRMan. All of these procedures are valid only in RIS-mode.
The RiIntegrator procedure is used to specify an integrator (built-in or otherwise). Integrators have their own set of parameters (see the Integrator Reference) and may expect the renderer to schedule work in a particular manner.
Integrator "PxrVCM" "handle" "int maxPathLength"  "int mergePaths" 
RiBxdf is used to assign a Bxdf (and optionally, a volume) to a surface. Bxdfs take precedence over RiSurface when an integrator is active but are ignored when no integrator has been specified. As with integrators, Bxdfs have their own sets of parameters; see the Bxdf Reference for details. For details on volume integration, please consult Developing Volume Integrators.
Bxdf "PxrDisney" "dis1" "reference color baseColor" ["mixer:result"] "reference float roughness" ["tex1:result"] "float metallic" 
RiPattern is used to wire in textures and patterns. As with integrators and Bxdfs, patterns have their own parameters (input and output). Consult the Pattern Reference for details.
Pattern "PxrTexture" "tex1" "string filename" ["checker.tx"]