RDAs
By default, foods that have RDAs associated with them (for example, Calcium) will show both the actual amount and the percentage of the RDA associated with them:
By clicking "Options" you can change this behavior:
Custom RDAs
The Nutrition Tool allows you to set your own custom RDAs, including ones that aren't normally set (for example, you could set an RDI for calories). To do that, click the "Custom RDI Settings" submenu in the options menu:
Clicking "Reset to Default" will return the RDAs to their default values.
The values set here will also affect the percentages shown in the RDI Graph.