You can also thread the leader through the front portion of the fly line a 1/2 inch before tying the Knot with a needle.

This knot will go through the guides so it is important to put some Pliobond or aqua seal on the knot so it won't hang up. 

You can also thread the leader up the fly line end and pull 4"-6" extra leader line through to tie the knot.

This knot is also used to make float stoppers. Just substitute a small straw or hard plastic tube in place of fly line and use rod wrapping thread in place of the leader material.