Below are some helpful tips on how to add your Google adsense to your feedbuner.
First you need to sign up or if you have a google adsense account already just sign in.
Now click on get started this is located at the bottom of you ads report overview page.
Then on that page you will find an invitation link below on that page this will help in add your feed to adsense.
Now you will have to send a message to adsense support email address email@example.com and make sure you send your feedbuner and adsense username and password to them and wait for their reply.
After you have received a successful message from them that means moved to a new account. And your whole history stat would go rise even more than the last 25 days.
If you still feel like doing this the other way, you can still go to www.google.com/adsense and click adsense for feed below your ads section and then you can begin.
feel free to ask any question below in the comment box thanks