Hi UVD,

Are you sure you are using the correct shader? Your screen capture does not show the correct shader name. I just opened up the one I linked and the displacement info is in there. 

At any rate, here's the screen grab of the displacement info. 

@ 50parsecs: You are correct, displacement turns the infinite plane into a large standard plane. I just always lay down the infinite plane because it's larger than the standard and then I replicate it if I need to. For most water shots, I keep the angle of the camera low enough that I actually don't need an infinite plane at all. If the camera is higher, then I'll use an infinite plane because you don't really need displacement - all the shaping can be done with bump or Normal bumps.