When you complete the Request Header dialog box, you must add a value to match against the condition. This value must match something in the Referer Header, which is used to identify the source of your traffic.
It is best practise to enter the domain of your referrer in the Value text box, as shown in the following examples of common referrers.
Use a value from the following list for the most common social referrers:
Use a value from the following list for the most common search referrers: