To add to what tcmeyer said… mark the blade with a Sharpie, clamp it near the handle, set the angle you want, and see where it removes Sharpie in the belly to tip area. You can adjust this by tipping the knife up or down.
It’s a common misconception to think the blade needs to be clamped “near the center of the apex”. You may want to take a look at this page for a bit of info on angle change. Then this page for positioning the knife… except in your case, instead of moving the knife back and forth, you can tilt it up or down to get a similar outcome.
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