How much fabric softener should I put in the dispenser, and are there any restrictions?

Dilute all liquid fabric softener with water for a total of 1/4 cup (60 mL) and pour it into the fabric softener compartment — do not overfill, as the dispenser holds exactly 1/4 cup (60 mL). Use only liquid fabric softener in this dispenser; do not use fabric softener dispensing balls, as they will not operate correctly with this washer. (Page 13)