I find one of the funnest things to do when making recipes, is to occasionally forgo style guidelines, i believe there are many amazing beers that have come from this practice.
In most commercial breweries, i beleive they usually use about 10%- 18% rye. wiht ten percent being jsut for a dry finihs to compliment hops, and 18 being a tad of the spicyness, if i were doing it i would personanly go with somewhere around 25%.
BYO has some great articles on amber recipe formulation and has an alright one on the use of rye, if no one comments atleast those may be more help than i can.
http://byo.com/stories/article/indices/11-beer-styles/127-american-amber-style-profile