Houdini 19.5 Lessons and Project Files: https://www.sidefx.com/tutorials/foun...
To add kinematics, you need to break the current hierarchy where the feet are under the COG. You can break off a few joints and reparent them to build the hierarchy you need. This reparenting happens off to the side then you will blend the results back into the original skeleton hierarchy which is important to make sure the bone deform functions properly.