I'm a health educator by profession. While the female condoms were not created specifically for use with Anal sex, it can be used for that purpose. Typically when used for Anal sex, take out the ring inside, apply lube to the inside and outside of the condom. Put the condom on the erect penis and slowly slide the condom inside. With one or 2 thrusts, the condom typically lines up along the anal walls.
I personally haven't used it, however I've heard mixed reviews. Some men like to take that ring out and use it as a cock ring... to each their own. I'd like to hear some reviews as well.