If you wanna put a loop into reason,the sample must be converted to a wave or aiff file.once you do that open up the nn-xt and then open up the remote editor.you'll see a folder in the upper left corner that says load sample,click that,then it'll open up, and where ever you have the file,let's say you have it on your desktop,go to it and select it.thats it...
This joint was done,vocals,samples,using the techniques i've said, and all on reason.
it's good to make a folder to put your samples in so they'll be easy to find.