Once you have completed the first Form 1099-R you can enter another Form 1099-R.
Click on Federal on the left side of the online program screen
Click on Wages & Income
On the Your Income screen
On IRA, 401(k), Pension Plan Withdrawals (1099-R), click on the Edit/Add button
On the screen Here's your 1099-R info, click on Add another 1099-R