(Am using Mac OSX 10.6.7 to download my iso, configure USB stick, and then copy.iso to it) This worked for me - Insert 4GB USB Stick - Open Disk Utility, Click ERASE. Properly burning an ISO to USB is different than just copying the file.It's even different than burning an ISO to a disc.Adding to the complexity is that you plan on booting from the USB drive once you're done getting the ISO image on there.

How to install from USB Stick rather than CDROM Am using a USB Stick to install Ubuntu Server 11 on a Linux machine, rather than using CD-ROM. If you have downloaded an ISO image of another operating system, say Ubuntu Linux or Windows 10, and you wish to turn that ISO image file into a bootable USB installer drive using a USB flash drive or USB key, you’ll find the most reliable way to copy or ‘burn’ the ISO to that target USB volume is by turning to the command line of Mac OS X. Creating an ISO image from a physical disc or from a set of files is very easy to do however, through the use of a CD burning application, such as the freely available CDBurnerXP or ImgBurn. Notes on ISO Support: All versions of Rufus since v1.1.0 allow the creation of a bootable USB from an ISO image (.iso). If it can’t be chosen as target, choose another directory and copy and paste the created ISO file to USB drive after burning. To directly burn video files to ISO image file for USB drive, you could insert your USB drive into the computer and then try to choose it as target in the “Save to” box. You don't need a bootable installer to upgrade macOS or reinstall macOS, but it can be useful when you want to install on multiple computers without downloading the installer each time. These advanced steps are primarily for system administrators and others who are familiar with the command line.

Mac burn iso to usb apps