how much ? heh... you know, a splash. my grandmother, when i ask her about recipes, is notorious for telling me "then add just a little flour, just enough so the dough will come out nice, not too much, you know..." etc. it's an art, not a science.
i'd say about a coffee spoonful.
of course, it could be worse : my cousin told me the story of going to learn how to bake her new husband's favorite cake from her new sister-in-law. she came home furious.
"what happened ??" asked her husband.
"i asked her how much flour to use, and she said "i just fill up the bowl to the crack" !!"
heheheh.