In this situation, are you required to signal your intention to return to the right lane with the direction-indicator?

Yes. Every lane change, including returning to the right-hand lane after passing a parked vehicle, must be signalled. According to Art. 22 para. 5 of the Road Traffic Act, a driver is obliged to signal their intention to change lane in advance and clearly. The manoeuvre of passing an obstacle consists of two separate lane changes (to the left, then to the right), and both must be signalled.