Hi Peter.
They are two different things. The illuminated recticle lights up the cross hairs on the finder making them easier to see. I have one but I don't use it as I can see the cross hairs quite easily observing in my light polluted backyard. A dark site can be a different story where those cross hairs are harder to see.
An RDF is zero magnification. What you see out of them is exactly what you see in the sky. Whereas a finder will magnify putting more stars & feint objects within view.
I will post a pic of my set up soon.