I have full linux installed on my flashdrive. What i want to do is boot from this flashdirve. There are many tutorials in the internet how to install linux on chromebook, but i want have original system untouched. All tutorials says that i have to enable developer mode on choromebook, but i'm curious if it is necessary to such simple task as booting from flashdrive.

So my question is, how to go to multiboot on chromebook, something like pressing F12 on my laptop?