I hired an f-1 visa grad student as a sub-contractor. She filled out a w-4 and was payed just under $1,000. Which forms I should file? Should I have withheld taxes?

[mavitabile1]

I am self employed and sb-contract grad students all the time but this is the first time I have hired a foreign student. The work is directly related to what they are studying.

[RobertB4444]

If you hired a student as a sub-contractor you should have had them fill out form W-9, which is a certification of their legal ability to work, and not a W-4 which is a verification of the amount that you will withhold from an employee's paycheck.  

Either way, for a sub-contractor you need to issue a form 1099-NEC for the full amount that you paid them.  Contractors are responsible for their own taxes on the money that they receive so you had no need to withhold any taxes.

Go here for TurboTax's tool for creating 1099s.

Be aware that the deadline to file 1099s is January 31st, today.

[Opus 17]

Did you hire an employee or a subcontractor?  If you don't understand the difference, start here.

https://www.irs.gov/businesses/small-businesses-self-employed/independent-contractor-self-employed-o...

You have significantly more responsibilities toward employees than contractors.