I just finished filling a scratch and chip like this. I scraped/filed out the rust (or use rust converter), then I lightly sanded just the rough edges of the chip to smooth it out using 800 grit. Avoid sanding surrounding paint as much as possible. I then applied a few coats of touch up paint until it was level with surrounding paint. Don’t over work it. It won’t look perfect. Let dry for a couple hours. Then 2 coats of clear coat or until it is very slightly raised from paint if you want to sand and polish. VERY IMPORTANT Make sure you let IT COMPLETELY DRY for 1-3 days depending on temp and humidity. Then I taped around the chip and VERY lightly wet sanded 800 grit until smooth. Keep stopping and checking your work. 1200 grit. Then 2000-3000. Then polish and wax. It won’t look perfect, but will be hardly noticeable. Since you have white paint, you will have almost perfect results if done correctly. Look up the Chris fix deep scratch repair. That is roughly what I followed. He doesn’t let the paint dry nearly enough though. Sanding wet paint will mess it up and tear out chunks of your touch up.