try to use a thin pentelpen head. not the usual big one. to avoid smudging. and the head of the pen should be circle not a square head. I dnt know whats ur brand there, but I use Pilot pentelpen on IP autos
I have experimented with alot of permanent markers over a 20 year period. I thought the Retractable Sharpie was a good pen until I started using Staedtler Lumocolor 352. They are a bullet tip and dry very quickly. If your cards are warm or have been in a warm place the cards will dry before a player can flip them to the back after signing and should not smudge. They applicate very evenly and don't bead like some markers tend to do.
its just port players.. just use a bic ballpoint.. haha no just jkin.. the steadtler is great for autos and sharpies are ok to use also.. stay away from cheaper brand markers tho.. most dont like glossy surfaces....