Rate Duration Factors can be utilized for schedules which require multiple durations.  The rate duration factors can be accessed via the Rates tab sub menu or at the bottom of the Optimization Set-up. 

To enable other durations, simply tick the check box for each duration required, these durations will automatically be displayed in the splits grid.

Editing the Rate Factors

Rate Factors can be edited using the 'Rate' column.  Simply click on the duration cell under "Rate" column and type the required factor then hit [ENTER] to accept the changes.