I do this:
Here is one way to tie the neck knot:
https://www.youtube.com/watch?v=j2tdU7t9640
I’m using an M1909 reproduction headstall and halter. They were made to do together but are not physically connected. Some folks like to use a halter bridle (a version of which was invented by the Army and introduced in 1912; it was abandoned shortly thereafter as it did not have either the durability or the utility of the M1909 system which would then be used until 1948).
In some earlier Cavalry versions a halter and headstall were worn together and the “rope” was a leather strap that would be secured to the on side of the saddle at pommel. Depending on the length of the strap it would be coiled or looped, as required.
There are many roads to Rome, here!!!
G.