You can program the function keys or F keys (labeled F1-F12 above the number keys) on your keyboard using the Logitech SetPoint mouse and keyboard software.
NOTE: If you don't already have SetPoint installed, you can download it. See answer 360023192814 for instructions.
To program a function key:
Launch the Logitech SetPoint mouse and keyboard software.
Start > Programs > Logitech > Mouse and Keyboard > Mouse and Keyboard Settings
Click the My All-in-One tab at the top of the SetPoint Settings window.
Select your keyboard from the product drop-down menu at the top left.
Click the "F" icon on the left toolbar to display the F Key Settings screen.
In the Select F Key field, choose the function key you want to customize.
Choose the task you want to assign to the selected function key from the Select Task list.
NOTE: You can click the “?” icon for descriptions of the settings.
Click Apply to save your settings and then OK to exit SetPoint.
NOTE: Some settings shown above may be limited to certain devices.