Unlike the method used to create a OS X Mountain Lion 10.8 USB Boot Disk, when creating a Mavericks USB Boot Disk, things are done slightly differently.
Tutorial: How To Create a Mac OS X Mavericks 10.9 USB Boot Disk
In this Tutorial we'll be demonstrating How to Create a Mac OS X Mavericks 10.9 USB Boot Disk. Let's Get Started "What You'll need"
An Intel Based Mac System.At least an 8 or 16 Gigabytes USB Disk (Make sure to make a backup as all data will be erased). And finally, a downloaded copy of OS X Mavericks 10.9 Developer Preview. (Currently only available to Registered Apple Developers) VERY IMPORTANT Make sure that you have a backup of your hard drive whenever you're working with the Mac Disk Utility program.