A technique provides a system and methodology for treating a plurality of zones, e.g. well zones. A plurality of flow control devices is located along a tubular structure, such as a well string in a wellbore. Each flow control device comprises a seat member with an annularly located recess having a unique profile relative to the annularly located recesses of the other flow control devices. Darts are designed with engagement features sized to correspond with selected annularly located recesses. Each dart may have an engagement feature of a specific length designed to engage the corresponding recess of a specific flow control device to enable actuation of that flow control device once the dart is dropped through the tubular structure.