To be played at 1280x1024 at the lowest set UI Scale through video options. For this to properly work, select your DUI to impossible where you will see your username_server (for example, unlimit_demonsoul) in the top left of your screen.
YOU MUST DISABLE EVERYTHING IN YOUR RDX IN-GAME BLIZZARD MANAGER FOR THIS TO WORK.
Portraits will only be visible for your Player, Target, Party, Arena, and Boss frames.
However, these units will only actually display a portrait if they are at Max Health AND Max Power, unless you are a warrior, a druid in bear form, or a death knight, to which it is inverse and actually if you are at Zero Power.