hello
In the users profile page no keys are generated.
I use Wordpress Version 3.4.1 with "More Privacy Options" Version 3.2.1.5 and "Private Feed Keys" Version 1.0

I found this forum post that describes the problem.
kwekkeboom describes the incompatibility in the lower part of the posting.
http://wordpress.org/support/topic/plugin-private-feed-keys-feed-keys-not-being-generated

cheers
kuene