Yes, the SF95 will detect signals from the AT9. However, in order to correctly aim the antenna, you will probably be better served with a more advanced meter. Directv's instructions to aim and fine tune the dish involve aiming first at 101, then 119. The LNBF would need a voltage change and a 22 Hz tone to change to 119. A more advanced meter would have this capability. In order to do this with the SF95, you will need to change the signal strength setting on the receiver from 101 to 119 to allow the meter to "see" 119. Also, the "dithering" process (to fine tune the dish) will also be more difficult with such a basic meter, but it can be done.
And you cannot attach a meter directly to the 110/119 LNBF, at least without modifying the meter with pigtails that would plug into the 110/119 LNBF fittings. So don't worry about the warning.
The AT9 is a pain to aim, but with ALOT of patience, it can be done.
Good Luck
Al