Where to put the bundled metadata?

Hi,

This page:
https://source.android.com/devices/tech/security/dm-verity.html#heading=h.tkceh5wnx7z2

Has a 6-step "Implementation" summary, with the last step reading:

" 6. Concatenate the system image, the verity metadata, and the hash
tree. "

However - it fails to suggest what to do with the result.

My *guess* is that most of the steps 1-5 are being performed by "veritysetup create ...", however, that utility has no option to supply a key with which to sign with - so can someone tell me what steps I need to take next ?

Kind Regards,
Chris Drake