It is not necessary to redefine the RDI if you feel you have a metabolism in the standard and no particular diet plan. They are preset according to your height, age and gender.
But if you want to go on a diet, you can change the number of calories ingested each day and you can also modify any of the inputs if you have a reason to do so.
Eg increasing the need for iron if your doctor diagnoses anemia.
It is a form that contains all the calories and nutrients involved in the recommended daily intake by the governmental agency USDA.
You can change the recommended globally by typing in the lower left a factor in the text field and clicking the button
Click to restore the default values set by government health agency.
Finally save the values by clicking