The sliding scale is a function of the weight.   9 lbs, can lose 14 oz and
5 lb can  lose 8 oz.  However, my experience with good BF taking place is
that most I've seen only lose a couple of oz for a day or so, with weight
stablizing on 3rd day and gaining after that.
I would be more concerned with an 8 oz weight loss in a 5 lb baby too.  I
wouldn't think a 10% weight loss is very good for a tiny baby. As a tiny
newborn gets drier they nurse less well.  Sincerely, Pat in SNJ