Here is the amount used in a Blue Moon clone. It uses orange peel, not sure about just the zest.
.5 oz Bitter orange peel
1.25 oz ground coriander
Add to boil the last 5 minutes.
For a kit just boil your 2 quarts with the zest and coriander for 5 minutes, kill heat and add kit. Add to fermenter, top off with cool water. I would strain out the zest/coriander at some point before going into the fermenter.