Use this dialog box to find and choose the generated clock reference pin from the list of available pins.
To open the Select Generated Clock Reference dialog box (shown below) from the SmartTime Constraints Editor, open Create Generated Clock Constraint dialog box and click the Browse button for the Clock Reference.
Displays all available pins.
To identify any other pins in the design as the generated master pin, select Filter available pins - Type as Clock Network. You can also use the Filter to filter the generated reference clock pin name in the displayed list.