Page 96 - Peter Randall "The Craft of the Knot.."

STEP 2 Bring the running end from behind the pole and up over the
standing part.

STEP 3 Tuck the end under the center X-shaped part of the knot. If you
are able to place the Constrictor Knot at the end of the pole or another
object, you can use the following method.

STEP 4 Make a single turn around the end of the pole, then pull down
on the bottom part of the turn and twist it to make a crossing turn.