RouterBOOT booter 1.0beta3

Can anyone tell me how this booter work?

I tried to boot from Compact Flash contain my own image on RouterBoard 500 series and i got the following response:
CF BOOT FAILURE: kernel partition missing! :frowning:

How did you make this image? there are slight notes on how to make this in the latest RB500 manual. I think, it is enough for you to start. If not, see how the reference image is made.