I'm not familiar with the RB67, but the general rule is that if you have TTL autofocus you should use a circular polarized filter. Linear polarizers tend to confuse the autofocus function. Tiffen and Hoya both make excellent filters. I believe the "rotating frame" you mentioned is useful if the lens barrel rotates when focusing. The rotating frame allows you to hold the filter in one position while the lens rotates behind it. I don't think newer lenses rotate this way....

I generally recomend that you get the circular version, even though the RB 67 is neither AF or TTL Auto exposure.

All polarizer filters have a "rotating frame". The filter is able to be rotated to adjust the amount of polarization. You can use a linear polarizer on your camera; however, like Dave I would suggest a circular that way if you want to use the filter on another camera that has auto-focus you can. I use the Cokin system which allows me to use the same filters on all my cameras so while my medium and large format don't have AF, I use a circular polarizer so I can use the same filter on my 35mm bodies.