Check out the video I posted above. It explains exactly what Howard shot. The riser should be no longer than 12 inches. The limbs should be no wider than one inch at the riser and only .5 inches at the limp tip. The limbs should be built with what Howard called a “bulge,” meaning that two-thirds of the distance from the end of the riser fade-out to the string nock tapers down to 75% of the width and thickness of the base of the limb, then the remaining 25% of the limb narrows to 50%. The end result is a stable, thick-limbed bow with an elliptical tiller.
A lot of people sell bows that they call Hill style, but they are really just flat bows.
Plus, to be a true Hill style bow, you really need to build the bow twice. First you build a stave, then you add the glass. There are a few great bow builders who do this, but it is time consuming and not profitable enough to make a business out of it.