I've been using signature pad for years and am aware of how it works.For at least the past couple years it stores my signature so I only have to click to apply when using it for this feature. So that part again is not new.

It appears PS has added some feature where it will automatically apply my (assumed stored) signature when I am presenting a client for their "wet" signature.  So they are telling us they have added some new feature and nowhere can I find out how it works.