Radius ball shim

[Henry's Lady's Man]

I can't find my answer on existing posts, so I'll ask afresh to all the Model A Wizards... I seem to have no appreciable CASTOR, so I purchased a hemi-spherical cup-like shim with a hole in it from Brattons. Then, I found a really dumb You Tube video of some guys in Mass. "RichPins" installing it UNDER THE BALL! [Jeepers, these guys don't know how to communicate, and the dad gives rediculous half answers to his son, like "I don't know, I tighten it till it feels good"]. I'm convinced they are wrong and "bass-ackwards". Shouldn't it go OVER the radius ball? Only OVER the ball would push the ball down (lower it) and change the castor. Am I wrong or right here?
Also, is it fairly easy to pull the radius ball down to get this cup over the top of the ball (felt pad too)?
~ Chuck