The only way you get that sort of coverage is by using a v notched floor laying trowel, a 3 or 4 mm tiling trowel is unsuitable for this adhesive. I used F44 on the last couple of ply floors I did as I've always got a tub knocking around. If you haven't used it before it will seem strange how little you have to use but basically just spread the whole are you are fitting, leave for 20 mins or until it goes really tacky then fit. This adhesive will grab instantly and you won't get the membrane back up again so be careful. If you can lift it back up then you're trying to fit too early. You can walk on it as soon as you put it down and i'd recommend rolling it afterwards, I use one of these-