I can`t boot guixsd in macbook

[SergioBG BG]

Hi to all . I intended install guixsd in macbook 2009 and after download
iso and burn it with etcher in one usb I can't boot in my old mac , with
button start and option button nothing do.
With Debian buster no have problems with start , but guixsd is imposib.
The boot not show usb to start guixsd.
What am I doing wrong.
Sorry for my bad English , cheers