When you press the lower red button, an alert will sound and the display will show a red icon after a few seconds.

You don't have to touch the screen, just wait for your helpers.  

It is also possible to add the Smartwatcher icon to the screen and make it possible to trigger the alert by pressing the icon on the display, instead of pressing the red button. To make this option available, login to your watch management portal. Now you can switch on the "alert icon" setting in the "watch settings" menu.