For Smart Forms: in the remote checked systems implement the SAP Notes 2558283, 2613349.
For Adobe Forms: in the central ATC check system implement the SAP Note 2629856. In the remote checked systems implement the SAP Notes 2617401, 2613349 and 2617830.
Execute remote ATC check on your central system
In the ATC transaction just configure ATC check run series (click ATC Administration > Runs > Schedule Runs > Create (more on this in the Configuring Run Series in the Central System) over the package in your remote checked system, which contains your custom Smart Forms and/or Adobe Forms, which you want to check for SAP S/4HANA readiness:
Schedule the remote ATC run.
The SAP S/4HANA incompatibilities in the custom Adobe Form and Smart Form in the remote check system will be displayed in the ATC results and can be analyzed in detail:
Execute remote ATC check on your development system
If you are on your development system and want to check your custom Smart Forms and Adobe Forms objects for incompatibilities with SAP S/4HANA for example, you can run remote ATC checks in the ABAP Development Tools in Eclipse.
Just select the package containing your Smart Forms and/or Adobe Forms and use the context menu Run As -> ABAP Test Cockpit With… and specify the ATC check variant (e.g. S4HANA_READINESS_REMOTE).
The SAP S/4HANA incompatibilities in the custom Adobe Form and Smart Form will be displayed in the ATC results and you can analyze them.