Glad you're enjoying it!
When you have to play a card as ICE you place it on the royal with the closest value. In your example it would go on the King first, since 13 is closer to 3 than 16. Basically the lowest total value royal (including any ICE) gets the card. If there's a tie you can pick where it goes as ICE.
I haven't messed with boardgamegeek yet. I only just got used to DriveThruRPG but I'll definitely take a look, thanks!