Yeah, creata smapler into node and a ramp, delete the place 2d node for the ramp, then mmb the facing ration to the ramp, then in the window conect the facing ration to the u value of the ramp. Then connect the ramp's out colour to the reflectivity of the material that your using (you can mmb the ramp in the hypoershade and drag it to the reflectivity value in the attribute editor (not the value but the actual text that says reflectivity)
Then use a white for high refelctivity and a black for none, adjut the ramp postionings and the values of the colours to suit the model.
To test it out you might want to really overcrank the values so you get a feel of what its doing
I use the sampler info node fore pretty much everything to do with specularity (which is faking the hotspots for reflections tbh) and reflectivness, theres a lot of it on my pirate model that I did, heres a link toi a larger picture, theres fresnell on the reflectivness/spec for the eyes, skin, hat.
linkey to it.
"No pressure, no diamonds" Thomas Carlyle