The sign for "expert" is done by using an "F" handshape and moving
it quickly to the chin.
The contact is relatively strong, and the hold is extended.
The mouth morpheme is part of this sign. By that I mean, as you make
contact with your chin you puff out your cheeks a bit.
Another way to sign
"expert" is to use the TALENT sign.
You can learn
American Sign Language (ASL) online at American Sign Language University ™
ASL resources by Lifeprint.com © Dr. William Vicars