A picture frame is not required - in fact you don't need one at all. Fifth wheel hitches are made specifically to fit into the puck system. You have to specify the vehicle manufacturer since they are not standard across brands. Look at Etrailer.com
ClickyA picture frame might come in handy if you have a newer truck with the puck system, and an old fifth wheel hitch that needs rails to mount it - although I'm no expert on the subject - others will chime in I'm sure.
I recently bought the slider version of the B&W Companion pictured, and I'm very happy with it - very easy to operate.