How to use Pipe Variable?

Hi all,

I have searched youtube, google and this site to find out an example of setting up Pipe Variable, but did not find any except a few related questions and answers.

I have an existing curve to do the Pipe Variable(Surface-Freeform) but not sure how to get the value for the "Curve parameters for radii".  Can someone point me to an example on the web on the actual implementation of the Pipe Variable?  How different inputs are obtained?

Many thanks

Kyle