Can I advertise donating part of app proceedings without using apple pay for donations?

I am currently part of the development team for an app that intends on donating part of its proceedings to charities related to music teaching. We do not intend to let users donate through our app, but will conduct these donations using "our funds", obtained through the app. In our understanding, then, the app will comply to the acceptable business model issues from the App Review Guidelines (item 3.2.1, paragraph vi), in the sense that it wouldn't be necessary for our app to only donate to approved nonprofits.

However, we do intend to include within our app the claim that part of the proceedings will go to charity, explicitly stating the percentage of the proceedings to be used to this end. Is this permitted under the App Review Guidelines, and if not, what is the best practice for doing this?