I have been flintknapping since 1992. I use my initials, MJM, to sign my work along with the last two digits of the year. Over the years, I have used both ink and a diamond scribe to mark my work. I usually sign in the lower right portion of a point on the B side.

Diamond scribed initials and year.

Dr. Errett Callahan was an American archaeologist, flintknapper, and
pioneer in the fields of experimental archaeology and lithic replication
studies. He signed his work with a engraving pen.

Joe Ketter II. Traditional method copper Knapper. Diamond Scribed JKII, and with full 4-digit  year - 20xx. Most often Scribed near the bottom half of the B-side. I usually scribe with a diamond tip scribe pen, but have also used diamond engravers. Any points signed in ink/marker are also diamond scribed and dated. Most often inked directly over the diamond scribe. 

Diamond scribed lowercase dk. The d and the k are combined and a two digit year.

Signs in ink with full name and two digit date.

    Some of my earlier pieces were signed with marker but was quickly replaced with a diamond scribe. 

Makers mark. Hopper style signature. 

BE stands for Bill Earnhardt