You need to set your displacement bound in order to see displacement. For performance reasons one is not set by default. Use small values at first, large numbers degrade performance and small numbers may truncate the displacement.
if you have clipping, increase the value slowly.
To match Displacement from previous version of RenderMan, the following conversion may be of use:
To get a similar tessellation level, using a shading rate (deprecated) value of X would translate in using a micropolygonlength value of sqrt(X):
shading rate = 0.25, micropolygonlength = 0.5
There are two types of displacement, scalar and vector: The source of both types of displacement can be procedural or textured.