"Respondez s'il vous plait" is a French phrase that is commonly used in formal invitations to ask for a response or RSVP. However, there are other phrases that can be used interchangeably to convey the same meaning. Some synonyms for "respondez s'il vous plait" include "please reply," "kindly respond," "let us know if you can attend," "RSVP requested," "your reply is requested," and "please let us know if you will be attending." It's essential to include such requests in formal invitations so that the host can plan accordingly. Using any of these phrases shows that you are courteous and respectful of the host's time and efforts.