Making a smart key is basically creating a button for each employee class and grouping them to use the same spot on the touchscreens. So the Smart Key button actually takes you to the Smart Key Group setup, and you add the keys from there. Its the same as creating a regular touchscreen button, except that you're going to assign an employee class as well.
In the POS configurator go to Devices / Smart Keys
Add a Smart Key Group, (Upper blue plus sign), and give it a name; Happy Hour or something like that.
Set the Rule Type to Employee Class and leave the Operator set to Equal.
Add a Smart Key to that Smart Key Group for each of your employee classes, (lower blue plus sign). Select an employee class and fill in the relevant button fields for that class. Enter the employee class name in the Smart Key Name slot, it just keeps things clear.
When you're done, go to the touchscreen designer and add a button to test it out. Set the category to Function:Smart Key, and in the dropdown below it select your new Smart Key Group.
Start OPS and give it a test. If you missed any employee classes in the setup the button will show as a blank space on the screen when somebody with that employee class is signed in.