Hand gesture recognition is an emerging application of portable radar sensors. Most of existing works rely on Doppler-radar sensors for non-contact detection of hand motions. However, Doppler-radar-based hand gesture recognition utilizes only the Doppler effect to extract motion features, which imposes a stringent requirement that only one motion is in the field of view of the sensor, leading to limitations in practical applications. In this paper, we investigate the feasibility of using an FMCW radar sensor with range-Doppler processing to recognize human gestures when multiple moving subjects are present in the sensor's field of view. A custom-designed portable 5.8-GHz FMCW radar is used. By using range-Doppler processing in the range-Doppler domain, experimental results enable to verify the effectiveness of the proposed radar sensor in hand gesture identification with the existence of interferences from surrounding moving targets.