I'm not sure that applies in all cases, particularly nvidia cards...many (myself included) can't force AA from Inspector or nvidia tray without imultisample>0. It seems the nvidia stuff needs minimal AA activated in-game to enable 'enhancement' externally (to whatever values you wish). I set my imultisample=2 then tinker in Inspector by 'enhancing' AA.
Have you tried.....In launcher set both AA/AF to off.
Then in Inspector.....
Select "override any application settings".... this way Skyrim has absolutely no say in anything!
And for AF select "user defined"
The drop down list for AA settings is huge,,,are you selecting "0x0000005 (Elder Scrolls 5 Skyrim)" for the "Antialsing - behavior Flags"?
I should post a screen of my settings i am really happy now with how smooth the game is playing now. I have changed a few more things because of reading i have done, and the new settings work great.