I use the Korean made Mon Ami Super Rolling pens, they work the best
for me. The ink soaks into the wood, without bleeding, enough so you
can't rub it out/off yet it's nice and clearly defined for reading.
Wax or oil finish overtop do not erase it. The really fine rolling
pens don't leave enough ink. Gel based inks hardly penetrate the wood
at all and rub off or smudge easily.

Bart.