There are many different pathogens which can cause the kind of leaf spotting seen in the photos. Some varieties of rhododendron are more susceptible than others, but all are prone to infection, especially in years with cold, wet springs. These infections rarely threaten the plant's overall health to a serious degree, but are unsightly. A broad spectrum fungicide applied as a spray just as the new leaves are emerging may help as will systemic type treatments in early spring. All in all, though, most people growing rhododendrons on a non-commercial basis just learn to live with the problem.

The semi-circular notches on the leaf edges are likely from weevils. The bottom yellow orange colored leaves are typical of rhododendron leaves about to be naturally shed.

Finally found the leaves. Look here
http://www.flickr.com/photos/calees/6190906813/in/photostream/#/photos/calees/6190906813/in/photostream/lightbox/

Where on the plant did the leaves come from?

What does the rest of the plant look like? Can you post a picture, please?

Here is a link that might be useful: the leaves