When it comes to your officiant, its important to remember that this person, whether you know them well or not, is joining you and your fiance for life. Therefore its important to consider them when preparing your guest lists for various events.
The officiant should be invited to the rehearsal dinner and receive an invitation to the wedding. If applicable, you can invite their spouse as well. The rehearsal dinner will be another opportunity for you to get to know the officiant. Socializing the night before the wedding may make you more comfortable with him or her on the big day.
(sourced from emilypost.com)