No but you can call them and ask them if they are coming but you should demand an "for sure" RSVP.
RSVP is a French phrase Repondez s'il vous plait, meaning ' please reply ' RSVP to.......
It is acceptable, but ask for an RSVP so you know it was received.
RSVP
RSVP by Close of Business.
RSVP Gallery was created in 2009.
RSVP is an acronym for the French phrase "Répondez s'il vous plaît"
RSVP is used as-is in America, even though it is a French term.
RSVP Stands for Respondez Sil Vou Plait (sic)
Please RSVP before xx/xx/2010.
The abbreviation "RSVP" stands for "répondez s'il vous plaît," which is French for "please respond." There is no specific abbreviation for the term "RSVP."
If you see this person's) often then when you run into them and ask why they haven't RSVP yet it might simply be because they lost your number or just simply forgot. but if you don't see them on an every day basis give them a call a reminder wouldn't hurt anyone! :)