The % value for the vitamins, minerals and sodium remain the same.
The % value for fat and carbs would change based on calorie level. The easiest way is to use your SP ranges. You get a range for calories and a gram range for fat, carbs and protein. Compare these amounts to the gram listing on the label. If the label indicates that a serving contains 20 grams of fat---you can easily so how much of your SP fat range budget this food uses up.
If the RDV's on labels are based on a 2000 calorie diet how do you estimate the values for a 1400 calorie low sodium diet. Should the values be higher for a lower calorie diet? For instance if sodium is listed as 100 mg. on 2000 calories, is it higher for 1400 calories?