Building water profiles using RO water

The water I use is RO (reverse osmosis) due to having a private Well. So my understanding is the RO water has very little minerals in it.

So I would need to add minerals/salts to match water profiles of specific cities if I want to try to mimic a style.

Can I assume that basically RO has 0 ppm of all salts and minerals and build my water with that assumption? Or should I still test the water to verify what's in it?
If I should have it tested where can I get this done at?

Example water profile:
Munich, Germany
Calcium(Ca): 75.0 ppm
Magnesium(Mg): 20.0 ppm
Sodium(Na): 10.0 ppm
Sulfate(SO4): 10.0 ppm
Bicarbonate(HCO3): 200.0 ppm
PH: 8.0 PH

True RO water should have nothing in it.
If you feel compelled to test it anyway: Ward Laboratories, Agricultural Testing, Consulting, Kearney, Nebraska