Withings binding

Hi, I’m new to openhab and I’m trying to setup the binding with my withing scales.

I am confussed with the instructions that say

n order to start the authentication process the user needs to execute withings:startAuthentication on the OSGi console whereas accountId is an arbitrary key also used in the openhab.cfg

I have tried to add withings:key=
I have tried to add withings:accountid=key

and then run
withings:startAuthentication key
each time, but I get the error

[.w.i.api.WithingsAuthenticator] - Couldn’t find Credentials of Account ‘accountId’. Please check openhab.cfg or withings.cfg.

What is the actual line I need to add to the openhab.cfg, I am very confussed on how to add an arbitrary key to the cfg file.

Any help would be great.