If your flag doesn't appear, check your spelling (and possibly capitalization). Some common alternate names are included (e.g. USA for United States); if you think you have one that's important and is not present, post on this template's talk page.
If your flag has so much white that it becomes difficult to see against the page background, then note such on this template's talk page, and it will be given a border. Currently these flags have this feature enabled:
- South Korea