Specifying account correlation using a rule cannot be performed using the Rapid Setup application onboarding process. Rapid Setup is designed for straightforward and simplified onboarding processes with a focus on quick configuration, typically using predefined templates and options. However, advanced configurations like custom account correlation rules require more detailed setup, typically done outside of the Rapid Setup UI, involving scripting or detailed configuration within the application definition.
Reference:
SailPoint IdentityIQ Rapid Setup Guide
SailPoint IdentityIQ Administration Guide (Account Correlation and Application Onboarding Sections)