Go to Apps → Manage your apps → Custom Field Suite
Click on Create custom field button on the right side of the screen.
Select Timezones and click Next.
Name and add a description to your field then click Next.
Choose the desired format
Enable or disable local time for the selected timezone
Choose between a 12 hour and 24 hour time format
Associate the field to the appropriate screens and click Create. You must associate a field to a screen before it will be displayed.