Dan John teaches the RDL using a snatch grip (wide apart)
Here is a PDF with a short article on getting the RDL
http://danjohn.org/II1.pdf
Here is a video - he talks about many things and it is all worth watching but starting at about 30:00 he talks about the Olympic pull - and in the process, teaches the reach back & extension of the RDL
http://thefitcast.com/?p=108