Adding agencies to Greenhouse Recruiting enables you to track them as a Source in your recruiting efforts. You can also invite individual recruiters from the agency to submit candidates through the Greenhouse Recruiting agency portal. The individual recruiters will be tracked as Referrers.
Navigate to the Agencies page. (Configure 
> Agencies)
Click Add Agency.
Enter the Name of the agency and click Create Agency.
To invite the agency to submit candidates through Greenhouse Recruiting, you will need to add at least one agency recruiter to the agency. To learn how to add an agency recruiter, click here.
Once you have added an agency, you will be able to select it as the Source for existing and future candidates.