This is the correct procedure, but the administrator account you are using by default does not have "unrestricted content access". This permission is not normally given because it may grant you access to content within your company that you may not be privy to. This is the kind of access required to "run-as" other users, since those users might have access to private or secret content.
Since the signature does not change, it's generally a one-time function to generate it for your Jive instance. As such, it might be simpler for all of us if we generate it for you. Start by contacting Ryan Rutan. He can help you figure out what's best in your case.
Hope this helps.