The hammock side gets a girth hitch. Click HERE
. I don't see how an adjustable loop would add anything to that attachment.
If you're thinking of simply cinching down an adjustable loop, a girth hitch is much more secure than that because the more weight you put on it, the tighter it gets. A cinched down adjustable loop will not get any tighter than you can pull it.
To add more security, make a few wraps around the hammock end before you form the girth hitch. This will wrap the bury of the fixed loop around the hammock end and bring the end of the adjustable loop's bury right up to the hammock so there's no extra line. Good luck!