I ran into some problems trying to fix certificate based subscriptions for rhel6, these two articles were very helpful so I suggest you have a look at them before reading on:
- Can not update a system that is registered with subscription-manager
- Which product key file maps to a version of Red Hat Enterprise Linux?
I was able to register the machine and subscribe a valid pool to it, but when listing the available repositories with yum, ‘This system has no repositories available through subscriptions.’ returned. Redhat support informed me I had to install the appropriate product license key myself.