There are no minimum or maximum thresholds. Your need will depend on the number of candidates you want to add to your workforce. If the on-site recruitment team has their plates full and cannot dedicate the time and effort for other HR activities, then partnering with an RPO agency makes total sense. Your RPO partner will take over recruitment and offer some breathing room to the HR team.
Also, partnering with an RPO agency has other benefits apart from recruiting quality candidates. You can improve the overall candidate experience, reinforce your company’s branding activities, reduce attrition (improve employee retention), and optimize recruitment costs.