Add .toUpperCase() after referrer. This method turns the string into an upper case string. Then, use .indexOf() using RAL instead of Ral.
if (referrer.toUpperCase().indexOf("RAL") === -1) {
The same can also be achieved using a Regular Expression (especially useful when you want to test against dynamic patterns):
if (!/Ral/i.test(referrer)) {
// ^i = Ignore case flag for RegExp