Use the following procedure to layer two sounds on the FP-4F:
1. While holding down a TONE button, press another TONE button. The two selected tones will sound at the same time.
2. To select a variation tone for the 1st selected tone, use the + / - buttons to the right of the display.
3. To select a variation tone for the 2nd selected tone, hold down the 2nd selected tone button and then use the + / - buttons to the right of the display.
1. While holding down a TONE button, press another TONE button. The two selected tones will sound at the same time.
2. To select a variation tone for the 1st selected tone, use the + / - buttons to the right of the display.
3. To select a variation tone for the 2nd selected tone, hold down the 2nd selected tone button and then use the + / - buttons to the right of the display.