Here is a link to help you find the point. It is in the lower jaw, below the corner of the lip. http://www.innerbody.com/image/skel01.html.
If you poke around on your jaw, you can feel these holes. Pressure points are located in weaker anatomical structures. A foramen is a hole in a bone through which nerves and blood vessels pass. The mental nerve, which is part of the mandibular branch of the Trigeminal Nerve, passes through this foramen. I think it is M-HN-18 (miscellaneous head neck 18) correct me if I am wrong but we usually just call it the mental foramen.
You can treat it as if it were on the stomach meridian. It is one of my favorite points because it does a lot.
You can hit it, I like to use my palm. Hit it down or down and towards the center. You can dig in to it with a knuckle. Use the same angle. It weakens the neck and helps you move the head so you can get a choke or redirect the head so uke is off balance for another technique.
So take it to the mat. Enjoy and post your ideas.