Dress Code...

I have to let guest know that they have to dress formal, but not black tie. The men on FH side are not to fond of dressing up. How should I let them know, without being a bridezilla?

Any suggestions?

Since you're getting married somewhere other than the hall, you would put all reception info on the reception card.

Example:

Formal Reception
at six o'clock in the evening
Bridgeview Yacht Club
Island Park, NY

There are a ton of ways to do it but virtually all reception cards have a place where you can throw in 'Formal' in front of Reception.