Inlay substitution for fine lines

I inlaid a small butterfly (actual insect with wings) using 1/8-inch material into a table top and would like a suggestion as to how to depict the antenna that is not thick enough to use an actual inlay material. I am thinking of using a regular ballpoint pen before applying the water base urethane after testing it on a scrap piece to be sure the ink does not run. Any better ideas?

Submitted by larryouel1