To fit a peep-sight to a compound bowstring, first tie a few turns of bright coloured thread around the bowstring. The thread should not be tied too tight, as it should still be able to slide up and down the bowstring. Have the archer come to full draw and then slide the thread until it is directly in front of the aiming eye. Come to full draw several more times, so the archer can check that the thread position is correct.

When correct, this location will be the centre of the peep-sight. To insert the peep-sight, the bowstring has to be split evenly with an equal number of strands each side. The easiest way to do this is to put the bow into a 'Bow Press' to take tension off the bowstring. Split the bowstring strands at the marked location in line with the bow. (In parallel with the arrow direction.) As the bowstring is twisted and depending on type of compound cable set-up, the bowstring will usually twist approximately half a turn from rest position to full draw position. The archer will have to draw the bow several times to check the location of the peep-sight and to check that the peep-sight 'rotates' to align at a right angle to the aiming eye.
When looking through the hole in the peep-sight, it should appear round, not oval shaped. Several adjustments may be required to get the alignment correct.

Before shooting the bow, temporarily tie the peep-sight in the bowstring so it will not come out when the bow is shot. Shoot several ends of arrows to make sure the peep-sight is correctly aligned. When satisfied that it is, then secure the peep-sight by tying several turns of serving thread around the bowstring above and below the peep-sight, so it cannot slide up or down.