How to claim Form 8233 income deduction?

Ref:

https://ttlc.intuit.com/questions/2265975-how-to-claim-form-8233-income-deduction

1. Go to the Federal Taxes tab, click on Wages and Income. 
2. Click I'll choose what to work on.   (If you do not see this, just skip this step is fine)
3. On the “Your Income Summary Screen” scroll down to Less Common Income
4. Next to Miscellaneous Income click on  Update  or Start.
5. On the screen "Let's Work on Any Miscellaneous Income" choose Other reportable income (start or update)
6. Answer yes, and then enter "China-US tax treaty, exemption under article 20" in the description and the amount as negative number next to your name. Now you said in another post that you cannot enter a negative number, I tried and it worked, see screenshot.