My daughter Loghyn (also 14 mths) gets about 1/8 tsp in every 8 - 10 ozs of liquid she drinks (except milk . . . that just sounds too revolting to me!) and then we salt her food too.  Her sodium levels are great and so is her blood pressure. 

When she was still on formula, we used 1 salt tablet for every 8 ozs of formula.  Same thing with juice.

This is just what her ped endo told us to do though . . . I think every child is different.

Jess