The RDA for calcium is very high, in my opinion. Many cultures eat very little calcium and yet have almost zero occurrences of osteoporosis, and other bone related disease. As for potassium, just make sure you eat plenty of veggies and you'll be fine. No need to fret, unless you like to dump the entire salt shaker on to your food.
If you want more calcium, eat spinach and other dark leafy greens. Or bone marrow.