I have a bootable USB stick with the latest Ubuntu on it. To create this bootable pen I used Rufus in Windows 10. Is it possible to use this flashpen on my Chromebook? Or do I need to have produced it on Chromebook first? I do not know how to make the Chromebook boot from flashdrive. There are no F keys on the Chromebook so the idea of pressing F12 key during boot-up is out of the question.