I’m testing the K8 Pro with the iMac and it has a Windows Bootcamp. It won’t let me hold the Option/Alt key to go to the Mac startup disk screen. Any advice?

Our keyboard uses USB protocol while Apple's keyboard uses SPI protocol.

The difference is the USB protocol has a very wide capability while SPI does not.

Here is a solution for this Bootcamp.

1. If your computer is booting completely shut down, just hold the "option" key on the keyboard.
2. If you are rebooting your computer, you need to constantly hit the "option" key to enter Bootcamp mode.