Looks like ProSeries is still not supporting Form 7203 in the S-corporation program. 

The answer in this Q&A flow from an Intuit employee says to prepare separately and attach before eFiling. 

Intuit: yes we understand that the IRS doesn't say that it has to be attached to the F1120S filing. However, every other software system and CPA is preparing the form as part of the F1120S. So our clients and their preparers all expect this form. It is rather lame of ProSeries to not allow this form to be part of the basic package!