You should face the driver towards the listening area, port to wall, more than 8" from wall would be best but if thats all the room you have, try it and see how it sounds. If it's too much try stuffing a small pillow behind the sub, I have a small pillowy thing behind mine and it sounds a little better with it there. I'm on my third and final positioning/configuration for the F12. Using a blind test, so far 3 people have been unable to pinpoint the direction of the F12's positioning, 2 actually pointed to a mid rear position the other dead centre, straight ahead, the F12 is placed at the left front, beside my left main.
New years day, District 9, It Might Get Loud and The Hangover. Just hope my hangover is gone before I watch that one!
Happy New Year all!