Use to tie loop in end of leader. Stronger and easier to tie then perfection loop, but not quite as small or neat.
Form a loop in the end of leader.
Make a simple overhand knot in the double line.
Then bring the loop end through the overhand knot again. Lubricate and tighten by pulling on the loop end with one hand and the standing leader and tag end in the other.
Trim the excess line.