I began marking marking knives a good many years ago. In a way, I see it as a rite of passage for woodworkers.
In 2009 I designed and made special marking knives for detail work and dovetails. The article how to do so is here:
http://www.inthewoodshop.com/ShopMadeTools/A Knife for Marking Dovetails.html
I made many, mainly as gifts.
About 6 or 7 years ago, Chris Vesper (best toolmaker around?!) asked if he could produce them under his name. Chris is a good mate, and it was quite a compliment. He now makes these (I have no financial link) ...
You can, of course, make your own. See my link above ..
Regards from Perth
Derek