We use ProPresenter to do lower thirds without any additional broadcast card. We create slides with white text on the lower third of a black background and use our switcher's luma key. It works great!
Even when we use the chroma key with our "blue wave" lower third for our nursery announcements it still looks good, even though the luma key results in a semi-transparent lower third.
Mark Petereit - iOS Development Team Leader
Family Worship Center, Florence, South Carolina