Of course it requires atmospheric pressure!
There is no way for the water in the downhill slope of the siphon to 'pull' water upwards in the initial up-hill part, and for that part you NEED the external atmospheric pressure to instigate a pressure gradient in the initial part of the siphon.
Sure, it's gravity in the 'downhill' part of the siphon that exerts a partial vacuum in the upper part of the siphon, but without the external pressure it wouldn't work.
The linked document is also full of rubbish. It insinuates that the cohesion required to 'pull' the water up the hill comes from hydrogen bonds! (snort!)
It would be very easy to install a manometer in the topmost part of the siphon and show how the pressure changes.
Also, it's childs play to show that you can't suck water more than 10m uphill, a figure that maybe just happens to coincide with the atmospheric pressure? Please!?!
Even the wikipedia gets it right, unlike this Oz PhD. (Wonder what mail-order university he got his certificate from.)