Employee Referral - Text Box

Summary

Hello, I'm hoping to find direction on how to build a text box on the candidate application which will allow a candidate to list the referring employee's name. Thank you in advance

Content

Hello, 

I'm hoping to find direction on how to build a text box on the candidate application which will allow a candidate to list the referring employee's name. 

Thank you in advance for any step by step instructions you can provide.