Proper way to RSVP to a wedding invite when unable to attend?

I recently was invited to a wedding, but am not able to attend. The invite included an RSVP card, but the card does not allow me a "choice" of saying that I am unable to attend.





Here is an excerpt from the card...





"Please reply by [Date]





Name_______________________________


Number of persons_____"





Maybe I'm just overly sensitive, but it would seem tacky to write "0" in the number of persons line.





How is the best way to RSVP in this instance? Should I bother sending back the RSVP card?
Proper way to RSVP to a wedding invite when unable to attend?
On the card it self right your name and say UNABLE to attend. Leave the number of persons blank....Or add a line and say UNABLE to attend...





It is odd that there is no line to check unable to attend....





Good Luck
Reply:Actually, you have the answer yourself, and it is not tacky. Write "0" in the number of person line and your name in the name line. And yes, ALWAYS send back your rsvp card whether you can attend or not. Someone is in charge of comparing the invite list to the RSVP list and tracking the number of people that will be attending and who has and hasn't responded. Then they have to track down the non-responders and it really is a pain.
Reply:EDIT the reply by including your name and adding "Ongoing wishes for the new couple's happiness in my absence."
Reply:I think your instinct is correct and it wouldn't be in the best taste to insert a zero on the number of persons line.





I think it would be better to send a brief letter written in the third person, e.g. "SoCal Dude thanks Mr and Mrs G Brown for their kind invitation to the wedding of their daughter Zoe to Mr Anthony White on Saturday 27 June 2009 but regrets he is unable to attend due to a previous engagement."





(This is assuming the wording on the invitation card is in the third person?)