The “Misc Chgs” field can be accessed from RA Open and from RA Close.
From RA Open, go to Subwindow T
From RA Close, go to Subwindow E

When the cursor is in the “Misc Chgs” field, press Shift/F5 to invoke a pop-up window of your "miscellaneous" type charges. Add the charge(s) to the RA in a manner similar to adding options by entering a "C" next to the item. If the charge for the item can be edited, pressing (RET) will move the cursor to the next column where the amount can be edited. The total of all miscellaneous charges will display in the “Misc Chgs” field upon exiting the pop-up window.