How do I press the Fn key using a PC keyboard on a Mac?

You can use an application like ControllerMate to assign custom actions/scripts to keys and controllers.

I found this post helpful:

http://david.rothlis.net/keyboards/microsoft_natural_osx/

The Function keys (F1, etc) behave as such (as opposed to brightness, volume, etc), regardless of what you set in the Keyboard preference pane. If you press “F Lock” the F keys simply do nothing. Luckily the F Lock remembers its setting across reboots.

There is no Fn modifier key as on the Mac keyboards.

KeyRemap4MacBook allows you to map the F keys to the usual brightness, volume, etc. but then you’d lose the normal F keys.

The Fn key on mac keyboards is a hardware driven feature.

What are you trying to accomplish?

I have a Microsoft Wireless keyboard attached to my MacBook Pro and can do much of what the function keys do from this -- once I installed the drivers.

For example, I can:

• hit the volume, mute keys and play/pause to control audio
• hit the "mail" key to go back to mail
• I have F keys for Exposé features (e.g. F9 for all windows display, F10 for application windows

(Note that in Keyboard Preferences, I have "Use all F1, F2, etc. keys as standard function keys" checked)

I think the only feature that Fn provides that I cannot duplicate on the Microsoft keyboard is brightness control