I'm trying to install Ubuntu 12.10 on my macbook. I downloaded and put it on a usb stick as per these instructions. Everything seems to work fine until I restart my comp and try to boot from the USB: The only option it gives me is macintosh hd. The same happens when I try to boot it for another mac, so I know it's a probably with the USB stick and not my computer.

I've tried erasing everything on the USB drive and re-doing the whole process a few times. When I erase the drive with disk utility it wants me to choose a format, so i've been using MS-DOS (FAT)

Any ideas for what might make this work?