In short, if a program is not signed by a security certificate (provided by Apple), then under the default configuration (most users), OS X will not allow the app to run.
If you try to run a Mac application that is not signed, GateKeeper will display the following message:
Getting around this restriction is easy, but many Mac users don't know how.
In your instructions, tell your users that if they receive this message, they simply need to right-click (or control-click) the app and choose "Open".
You can, however, digitally sign your Macify app and avoid this whole issue altogether.