I am in the process of relocating my RO system and adding a larger reservoir, and have hooked it up in several ways. I am going to explain this as if you have some basic plumbing skills and some wrenchs. First off, how much to did you pay? If it is more than $150 - $200, I would see if I could return it. The ones I found on Spectrapures website are ungodly expensive. I paid less than $100 for my 30 gpd system and it came with a small faucet, and it has worked great for me for two years now.
Next question, do you have the 4 stage system that comes with the pressure tank/reservoir? Like the one in the attachment below?. If not, I wouldn't try to hook it to a faucet of any kind, the flow rate from mine when the reservoir is empty is just barely a trickle. If you do not have a reservoir that came with the system, you are probably going to want one, but thats a whole different post.
If you have the one in the pic and want to hook it up under your sink, I would get a faucet made for water filters, just like the one in the attached pic. You should be able to get this at a hardware store/HD/Lowes. They may even have a complete "hook-up kit" that would make this very simple. Then cleanly cut off the garden hose attachment form the output line on your RO filter. Then mount the little faucet where you want it. I put mine where my sprayer nozzle was on my sink after I got a faucet with the sprayer built in. Then attach the output line to the faucet with a 1/4" compresion nut, ring and brass insert. The hardware store people should be able to show you how to do this(much easier than explaining). It might help to bring a small peice of your tubing to the store so you get the corrct fittings. Now, for hook up to the water supply, I would get a three way adapter that hooks onto the water supply shutoff valve for your faucet. Same, get at HD or like. They should know what you are talking about, ask for the one that has a 1/4 compression for one of the outputs. They are usaully by the shutoff valves in the plumbing dept. Then pick up another 1/4" compression nut, ring AND brass insert for the tubing and hook it up to the shutoff valve three way adapter. It sounds long, but it is really very easy. I hope this helps.
