On second thought. I would omit the box 4 amount when entering this into 2019 TurboTax. By omitting the box 4 amount, TurboTax will not include the details of your made-up Form 1099-R in your e-filing; including the details is the equivalent of attaching the Form 1099-R to your mailed tax return. Since the tax withholding is not being claimed on the 2019 tax return, no "attachment" of the Form 1099-R is needed on your 2019 tax return.
