In order to get rid of clipping, you need to ensure the target level does not exceed 0dB. You can lower the level in the compressor, and/or use the Gain slider to lower the overall output level.
You can set the level meter in RadioBOSS to have the max at +3dB and it will also mark (in red) if you exceed the 0dB level - right-click the level bar to adjust it.