I wanted to try to Rapala knot on a crank, should I remove the split ring from the lure or no, or does it matter?

the rap knot is used mostly for crankbaits that dont have a split ring. Original raps are what they excel for. I use them exclusively on any hardbait that dont have rings >using them with split rings gives the line more of a chance to get under the ring and lose fish or impart the  action

I wanted to try to Rapala knot on a crank, should I remove the split ring from the lure or no, or does it matter?

Remove the split ring, the less hardware, the better !