I was at first told to tap Zed on the nose with a NO and redirect....I did this and I just didnt feel comfortable with it, the high pitched OW also revved(sp)him up more, so we do a NO redirect and if he does it again we do a really low loud NO like a growl, that works
We've given him the occasional scruff shake when he's gone right over the boundarys, especially in regard to our baby girl and this worked really well...we havent had to do this often at all and really it was around 11 wk mark maybe once or twice since.
He so much more settled now and we can have our daughter sitting on the floor Zed will caom and greet her with a few licks...he loves her ears

then I say thats enough and make him sit on his mat.
I think a nose "tap" is an individual thing.
Great thread for as newbie Rottie pup owners to read through