Love the name Rascal- appropriate for a Hav!
Is Rascal going after your hands? If so, not sure what else you are doing other than saying "No", but if you just pull it away, say "no" & then keep playing/petting after he may interpret that as a game and keep doing it so be careful. If he is going after feet, no advice we never had that issue at all.
I was lucky my pup had fantastic "bite inhibition" when I got her was & not stubborn about nipping. In addition she is super easy to train,
but when she did do it I followed some advice from others on the forum:
I stayed away from the word "No" -redirected with appropriate things to chew on- yelped loudly and stopped playing with her - short time outs, etc.
This might help too-
I also taught my pup the word "easy" at a young age... I used it at first when offering her to take toys, or treats from my hand to mean to do it gently. When she was
"easy" I would praise "good easy!!!!" and give a treat (or an extra treat of higher value in my other pocket when she took the initial low value treat gently) - that helped a bunch at her learning to be gentle; then was able to use the "easy" command too when she would jump up at our faces etc. Worked like a charm - except for when the Zoomies hit!
Nothing can calm her then except wearing herself out!