...

• Name
• Label (this is the UI name)
• Tags (necessary to see RenderMan attributes and edit them during interactive rendering)
  script_ritype  color
  renderman  attr

Image AddedImage Removed

Set its type and color value.

Add PxrMatteID

Create a Houdini buildarray node to connect to the Utility Pattern on the PxrSurface material. Then connect a PxrMatteID Pattern node to the buildarray as shown below.

...

In your PxrMaterialBuilder Network, add a PxrMatteID VOP.  Set the color as the user attribute above.

Connect PxrMatteID's resultAOV to PxrSurface's Utility Pattern.

...