Unfortunately since you made it yourself, it'll be very hard to predict exactly how much you need.
Here's one way to do it though. (Assuming your bottling bucket has a spigot, *or* you have a wine thief, either is fine)
Rack your beer from your secondary into your bottling bucket. Keep the lid mostly covering the bucket to keep all the nasties out. Add.... oh, let's say 1/3 of the first jar of lime essence. (I'm guessing the zest and the peel taste differently, and so you will want a blend. Am I right?)
VERY gently, stir with a well-sanitized spoon. Then draw a small tasting sample. Then add 1/3 of the 2nd jar. Repeat. Then another 1/3 of the first jar. Just keep going till it's where you like it.
Then, once you're happy with the results, add your sterile priming sugar solution, and gently stir one more time. Continue to bottle as usual.
I'm guessing - and this is JUST a guess - that you'll probably use both jars in their entirety. I'm making this guess because 1) 12 oz isn't much vodka, and 2) limes seem to have a very subtle taste, at least as far as their absorbency into a vodka solution. I could be (and probably am!) way off base with this guess.
On the bright side, if you have any left over when you're done... it's Grey Goose! It deserves to be drank!
Cheers and good luck!
