You can, but I strongly advise doing bench trials to see how it's going to affect the outcome before you dose the whole batch. Get a measuring cup based in millilitres and a syringe, which will be in cc's, but that's the same as ml.
Make up 5 or 6 100 ml cups, and then dose each one with your extract: 1 ml in one, 2 ml in the next, 4 ml in the next, and so on. Taste 'em all, and when you think you've hit the right amount, do the math and dose the whole batch.