Dell 5100cn Color Laser Printer - Manual (Page 165)

Setup printing Letter Plain 1 from Multipurpose Feeder
1. On the printer operator panel press MENU.
2. Press to get to Tray Settings.
3. Press to select Tray Settings.
4. Press to get to Paper Size. (ONLY ON 3x00cn)
5. Press to select Paper Size. (ONLY ON 3x00cn)
6. Press to get to MPF. (ONLY ON 3x00cn)
7. Press to select MPF. (ONLY ON 3x00cn)