RO water out of the tap, what are best products for conditioning and restoring kh?

In previous question, I meant hardness not pH.
What I meant to ask about the water that I am using for water changes is this: should I add RO Rite (Equilibrium) to restore minerals (my tap water is basically RO water with zero GH and KH) in place of aquarium salt and not worry about the pH as long as I do the partial water changes slowly as I have been doing. The dGH of the betta's holding tank is 4 and the dKH is 5, as of two days ago. You stressed the importance of avoiding osmotic shock (rapid change in water hardness) along with drastic pH change.