how to use the api_key?

I am trying to use the wordpress restful api without luck. Those requests that does not require me to submit the api key works fine, but when I try to submit my api_key with the request – I fail. I am trying to replicate what is found on the developers Restful api pages …could someone help me by writing an example get request with token ‘test’? for instance with a ‘GET /sites/$site/users’ type of request?

The blog I need help with is mostlywobbly.wordpress.com.