I have a mini hipster and my K2 fits in a cover, but I had to take the velcro off because the K2 was too tall.
I'm thinking the K3 might fit better since it is shorter. But I do know that the Oberons add some bulk and you may not be able to carry much else in the large pocket. I usually just carry a few dollars, drivers license, credit card, etc. in the front zip pocket and my keys in the back pocket.
deb