The sink has one existing hole, and 3 knockouts which are cut about half way through the material.
What are the best tools, and techniques for removing fixture knockouts on a composite granite sink?
Well Tester, as brutal as it seems, the prescribed method by FRANKE is to use a blunt ended large punch and a hammer. Set the punch dead center in the cutout and strike it soundly. Don't be too tentative, give it a good shot!! When i first saw my plumber do this on a kitchen job, I cringed! but it worked well. Weren't there any instructions with your sink? i'm just relating the way FRANKE recommends, maybe your brand might have a different method.