I just measured my shot glass...
If filled to the white line on the glass it measured out to be 1/8 the of a cup...so 1oz, Filled to the top of my shot glass it was exactly 1/4 cup...so 2 oz. I was never overly picky about an exact amount. A little more or less won't hurt I don't think. This is just what I used for 4 cups of feed. 1-2 oz was enough when mixed with the feed to coat most of it evenly without soaking into the feed.
I just mesure out my feed and splash the ACV on top and mix with a wooden spoon until I feel its thoroughly covered and there isn't a big glob of vinegar in it.
Hope this helps...If its clear as mud say something and I'll try to explain it better.
Check out this site. http://www.earthclinic.com/ They have tons and tons of listings on ACV and what it can be useful for. Cats, Dogs, Horses and Humans!!! Turns out this ACV is really good stuff. Fixes everything from pimples to thrush! 8)