Open Ableton and create a new project. Import the .sf2 file and create a new MIDI track. You can then drag the .sf2 file to the MIDI track. Create a new audio track, and set the track's input to the MIDI track with the .sf2 file. You can do this by using the drop-down menu next to the track name, usually set to "Ext. In". Arm the audio track for recording. Press recording while playing the MIDI track to trigger the SF2 sounds. Once you have recorded the desired amount of audio, stop recording. You can then export the recorded audio as a WAV file.