TourRadar no longer has a referral program, however once you book an adventure, you'll receive a promo code worth $/£/€50.00 to send to one friend or family member that they can use when they book with TourRadar! Keep in mind that this code can only be used one time and by those that are new to TourRadar, which means that if they already have a TourRadar account, the promo code will not work for them. Anyone who has booked a trip, downloaded a brochure, asked a question, etc. is not considered a new TourRadar patron.
You can read more at https://www.tourradar.com/invite.