I'll take a stab at this one.
Dosing NPK (if you use KNO3, KH2PO4, and K2SO4) will not affect GH or KH.
If you dose Calcium and/or Magnesium you will increase GH.
If you dose Calcium Carbonate specifically you will increase both GH and KH.
And if you dose any bicarbonates (not likely) you will increase KH.