It depends on the applicant's profile
Not every application requires a Responsible Third Party. For many applicants, particularly those who are employed with a sufficient income, a Responsible Third Party is not needed at all.
A Responsible Third Party is more commonly required for certain applicant profiles, such as students, where personal income alone may not meet the underwriting criteria.
How you will know
The application process makes it clear whether a Responsible Third Party is needed. If one is required, the tenant will be prompted during the application and guided through what is needed. If one is not required, the tenant can proceed without one.