A Robert Pattinson website is confirming Pattinson will have four songs on the soundtrack:
I have been able to confirm the following about Rob’s involvement in the “How to Be” soundtrack,
I can confirm that 4 tracks will have Robert singing and playing; his character in the film is a struggling musician, so they are songs he sings in the film itself. This news will be officially announced shortly….
From this post here.
Thanks to Monica on pattinsonlife.