There has been a dual time proposal within physics for some time now. Taking M-Theory as possibly the correct path, then if one is to add in this extra time as a dimension then you end up with a 12 dimensional frame. Check out

http://www.aip.org/enews/physnews/19...t/pnu462-1.htm and

http://arxiv.org/abs/quant-ph/0210207 and Opposite arrows of time can reconcile relativity and nonlocality

S Goldstein and R Tumulka 2003 Class. Quantum Grav. 20 557-564 whome I cooresponded a bit back on this same subject. It may not be exactly you're F theory, but a possible 12 dimensional model exists once such is combined with regular M-Theory.