The best way to use your new sighter is by balancing your leader configuration where the sighter will be attached. Do not attach your sighter to the very end of your leader, but instead, place it in-line where your leader is more robust. If using factory made tapered leaders, simply cut the tippet section and set it aside, you will reattach it later. Most factory leaders have at least 2' of level tippet.
To find the junction of leader and tippet, run your fingers along the fat section drawing the leader through your thumb and forefinger. As you pull the leader through your fingers, you can feel the diameter of the leader change. There will be a point as the leader gets thinner that the diameter will no longer decrease. If you have a tippet gauge you can be more precise by using that tool.
After snipping the level tippet section free from the base leader, you can tie in the sighter by using your favorite knot. I find that using a hemostat knot to be the strongest knot with the smallest footprint you can use. The tippet rings at each end of the sighter facilitate joining the sighter with the leader, thus saving both leader and sighter from being cut shorter.
Reattach the tippet section that you previously liberated from the leader. Tie the tippet back on the other tippet ring. You can further modify the tippet section to your desire. You can see in the illustration that I add another tippet ring for using a dropper fly.
Using tippet rings saves your leaders from being cut away after making tippet repairs. Simply re-attach the tippet of your choice to match conditions. I have used one single base leader for entire seasons of guiding and fishing only needing to modify the tippet.
Make your own base leader
French Slow Action Long Line Leader formula
50CM - 0.45mm mono
55CM - 0.40mm mono
60CM - 0.35mm mono
65cm - 0.30mm mono
70CM - 0.25mm mono
Sighter attached both ends via a tippet ring
2.5' 3x mono
Tippet of length and weight of choice depending on conditions.