To use the knife as a range finding device, you simply untie the lanyard, leaving one end attached to the butt of the knife. The lanyard is measured and cut at a specific length for range finding duty. Take the free end of the lanyard and hold it against your chin while you hold the knife (point-up) away from your body at eye level. The cord should be fully stretched and taut.
The four front close-range holes have been drilled for precise size and distance based on known fact that the average white-tailed deer measures 18" from the top of his back to his brisket. If you see a deer, you can gauge his distance by choosing the hole that displays this 18 inches of his anatomy. After you have found the correct hole, then just glance down and read the distance etched on the knife that corresponds with the hole. If measuring the distance of an adult human, the middle torso of a person is a pretty good 18" constant (neck to waist).
When using the long-range holes toward the rear of the knife, you must remember that these are set up to measure the distance of a moose, elk or human subject based on the known fact that the average moose or elk measures 24" from the top of the back to the brisket (or on a human, from the top of the head to the waist). Place the target inside the holes one at a time until the 24" of specified anatomy just fits inside the hole as you hold the knife at the correct distance away from your face (using the lanyard). After the correct hole is found, read the number marked next to the hole to find the distance.
