I will tell you from the old school perspective, I would have filled out the SR form, that covers the sound recording of the composition, and then if I really, really cared enough about a track like that, which you should because its extra dope for an RnB song, in the right persons hands they could make a platinum song out of it alone, then I would have printed out the sheet music from a software program and also registered the Sheet music....that would be the correct way to copyright sure fire, and that way you if you did want to sue.....A lawyer would not hesitate to touch your case...all of the above examples are sloppy and not so reliable ways to guard your work, I am speaking as an ASCAP member and one who has gone to many music industry conferences and heard how you do it and the difference between how you think it should be done, as always, if you care about your music please go the extra mile and protect yourself with REAL COPYRIGHTS....if you really want to seek statutory damages upon infringements you need to register properly
This explains why the "about their biz" producer will always register important works
In the United States, statutory damages are set out in Title 17, Section 504 of the U.S. Code. The basic level of damages is between $750 and $30,000 per work, at the discretion of the court.
Plaintiffs who can show willful infringement may be entitled to damages up to $150,000 per work. Defendants who can show that they were "not aware and had no reason to believe" they were infringing copyright may have the damages reduced to $200 per work.
Under 17 USC 412, statutory damages are only available in the United States for works that were registered with the Copyright Office prior to infringement, or within three months of publication.