spread cull

Hi! I have a question about the spread cull. I thought I was pretty OK at it, until I read the trick description of "Royal Flush Finale" in CC. For the trick you need a eight card set up (Ace, ace, ace, ace of spades, and the rest of the spades needed for a royal flush). It says that one cull...

Hi! I'm having trouble culling let's say the third card of the spread. I can do a proper cull in the middle of the spread, but if the card I need to cull is located at the very beginning (first four cards) of the spread, I don't know how to cull it so that audience wouldn't see. Any tips? Thanks!