Want something more feature rich than the UISQL editor included in ER/Studio?

Well you can by changing the option in Tools | Options | Tools within ER/Studio and point it to Rapid SQL:

Now any time either of the application wizards generate any SQL code (i.e. compare and merge, generate database), the code will launch in Rapid SQL.

Find out more about Rapid SQL here: http://www.embarcadero.com/products/rapid-sql