RenderMan for Houdini
RenderMan for Houdini (RfH) is an integrated interface to RenderMan inside Houdini. It is shipped with Houdini automatically. In other words, it is not a plugin that you need to purchase separately.
RenderMan 21.0 features are now available in Houdini 15.5.
To render with RenderMan inside Houdini, we do require the installation of RenderMan Pro Server, the renderer itself. See Installation and Licensing for more information.
More information can be found in the Houdini Documentation regarding RenderMan.