if i am thinking right....the bitz is indexed for cock feather out...if you twist your knock(90 deg)for cock vane down after the arrow is fletched...
put the arrow in the jig and turn the nock 90degrees.....
then turn the index nob the nob untill it clicks on the spot u need fletched...it should line up right betweenas long as you turned the knock correctly....or you could eye ball it...really its not that important if your off a little if you shoot a drop away or whiskerdoodad.

it is a pain to do just one fletch so i do all 3... other than that the Bitz is great

isnt there some leftover glue where the old fletch is....that could be your reference right there????????????????