For a pure TDC and PK shot I'll use the spread knob, but be careful it's very range dependent. At longer ranges a half a degree is all that is necessary.
+1/2°; 0; -1/2°.
Armistead
came up with a different way and that is to turn off the PK and aim the scope just in front of the bow and send range than shoot when the fat parts cross the wire. Gotta be quick doing this but it works very good.
Both methods take some practice but you get the hang of it quick enough.
Magic