No, the DR-6 works on the rectangular viewfinder like that of the D200.
I use a DR-5 on my D700 for macro photography. The D700 has a round viewfinder. It works well. My only gripe about it is that it doesn't have click stops every 90 degrees and gravity is always working on it to swing it around and point towards the ground. I always wrap a rubber band around it's base, where it attaches to the camera, to provide friction and keep it in place. I have yet to misplace the eyepiece you need to screw off, but its only a matter of time.
BTW, does anyone know why Nikon has 2 viewfinders, rectangular and round?