Janna,
We don't currently support the User Extended Fields of K2, just the built in ones. We'll add it to our list of things to investigate, but this is the first request we've ever had for this feature, so it's not high on our list. Additionally, you don't look to have an active subscription, which helps us to prioritize requests. If you choose to subscribe, let us know, so that we push this request higher on our to-do list.
Thanks,
Alex