A knot that is 3/4" wide is a big knot for a bow. I'd like to see a picture as well. Is it a dead, brown knot or a healthy, tight knot? With a knot this big, you must indeed make sure the actual grain of the limb flows around the knot in a natural way, on both sides. That means the limb will be wider at the position of the knot. The limb should be about 3/4" wider (the diameter of the knot) to compensate for its weakness.