REST Client (Get) with OAuth authentication

Hi

Please excuse my inexperience here...

I am trying to setup a REST Client to get data from a cloud based database using a well defined API. The Host uses OAuth to authenticate access.

I have a "Consumer Key" / "Consumer Secret" from the Host however I am struggling to see how to configure the REST (Get) transformation

At the moment, my URL looks like this:
https://api.xxxxxx.com/xxxx/xxxx/xxxxx/BalanceSheet?access_token=D5C2LxxxxxxxxxxxxxxxxJ15K . The Authentication / SSL / Headers / Parameters tabs are currently empty. On running this, the response is that the "Consumer Key is unrecognised"

Does the REST Client doesn't allow for OAuth authentication? If so, how do I set it up?

Any help would be very much appreciated!

thanks
Graeme