Using RO Water and Burton salts for the first time?

So I went to my local hombrew shop and asked about using salts with ro water instead of preboiling and dilluting my tap water with ro water. i dont know my waters profile though but know its extremely hard. I live in the Phoenix valley as well. He sold me burton water salts saying " everything is in there you just dont have to use as much" because with the beers I've been brewing i would like a softer profile and dont want to accenuate the hop bitterness as much.

I'm not sure if this is correct and if it is how much burton salts should I use?

The water profile depends on a few factors. Most importantly it must counter balance the acidity of the mash. The darker the beer, the more alkaline you'll want your water to be (more HCO than Ca). If you brew a pale beer, you'll want minimal salts in your water. Play with this calculator and it'll get you up to speed right away.

http://www.brewersfriend.com/water-chemistry/

Another thing to keep in mind is your Cl-SO4 ratio, equal amounts mean a balance of bitterness and maltiness. More chlorine, more malt flavor, more SO4 the more bitter it will be.

Thanks a ton man! That was a great calculator and it did bring me up to speed. So i hope that i just got done brewing my first successful batch with my own water chemistry. Once again homebrewtalk has come through for me in my time of need.