What was it withheld from? Here are my old notes. It's probably in the same place. Or some other 1099 forms have a checkbox to add more boxes.
Enter withholding on forms (like a 1099B) other than a W2 or 1099R under
Federal Taxes (or Personal for H&B)
Deductions and Credits
Then scroll way down to Estimates and Other Taxes Paid
Other Income Taxes - Click the Start or Update button
Next page scroll down to bottom section Other Income Taxes Paid
Click Start or Update by Withholding not already entered on a W-2 or 1099
