Explanation for sampled PXF analysis

I am trying to put together for myself why dividing a sampled PXF analysis by the slope of the signal translates into jitter.

I understand the units makes sense ([V/V]/[V/S]=[S/V]), but conceptually, i am trying to make sense of it. 

I want to start with what exactly a sampled PXF simulation does. I understand the difference between PAC and PXF, but what exactly is a sampled PXF trying to do?

The only definition i found is the following: "sampled analysis tells you the transfer function at a specific time-point in the periodic solution". I am looking for some more words