how can I manually add Schedule 3, line 13d

You can only enter this using Form mode.  Click on Forms.  When in Forms mode click on the 1040/1040SR Wks which will open the Form 1040 and Form 1040-SR Worksheet.

Scroll down the worksheet to Schedule 3.  On Schedule 3 Part II under Line 12 is the Other Credits and Payments Smart Worksheet.  On Line E enter the amount for Net section 965 inclusion.  The amount entered will flow to Schedule 3 Line 13d.

Thank you so much. It works!

The problem solved. Thanks for your answer!