I use Beersmith, it probably has honey as a fermentable but that won't help me know how much to use to get the hint of honey taste.
I'll probably use some honey malt like @The Baron suggested and/or just chuck 100g of decent honey in near the end of the boil.
Ah, OK. I thought you were targeting 10% of the fermentables (your post mentions 10% from honey) but I know what you mean about how much for the flavour ? You could add it during fermentation and then taste it.
Probably better to undershoot ?