Anyone use adsense for feeds? Looking for some clarification

I just recently decided to check out adsense for feeds. It's not like adsense for websites where you input HTML, you actually create a feed within adsense.

I already had a feed through my blog and website, have around 100 subscribers. When I go to create my feed in adsense it asks for my origional feed address so I put in the one to which I have 100 subscribers.

It creates the feed but shows me as having 0 subscribers. This leads me to believe they created a new feed instead of adding adsense to my old feed where I already have all these subscribers.

However I thought I read something online about how what really happens is they create a new feed that basically redirects to your old feed so new subsribers will see ads but the old ones wont'

Anyone use adsense for feeds and can offer some clarification?

There seem to be a ton of people on here with their own websites or blogs however whenever a topic about affiliate prorgams, adsense, etc comes up nobody has anything to say.