you mean a taste of 'citrus'?
If you want to add zest, I would add it to your priming sugar syrup at bottling. Maybe do zest from a grapefruit and orange into the corn sugar syrup, strain, and add at bottling?
the issue with doing it this way is you do not know how much to add. Typically with adjuncts like this, its best to pull an 8oz sample, separate it into 4 glasses, add increasing amounts of an 'extract' like this fruit essence, and taste each one, then scale it up to how much beer you have in the fermenter.
FWIW, many american hops, including amarillo, cascade, centennial, citra, and particularly simcoe, impart plenty of citrus notes into your hop character just by adding late in the boil or in some cases by dry hopping. Were magnums @ 60 minutes your only hop addition? Also, what do you mean by 'hoppy light malts'? Malts aren't hoppy, hops are hoppy.