While whether a ring looks good on your finger comes down to subject preferences, here are some options that are bound to suit wider fingers and make them look slimmer.
Split Shank Ring Setting
Split shank setting engagement ring for fat fingers
Open split shank ring setting. See it here.
The split shank ring setting is ideal for wider fingers because it creates the illusion of being a wide setting without being bulky. This offers excellent balance between your finger and your ring. There are many variations to the split shank design, from barely noticeable split shanks to very open split shanks. Choose the setting that suits your style.