Rosacea was not addressed in my book because I was trying to focus of first aid type issues. As a general rule, skin problems can be traced back to the liver. If the liver is unable to filter and detoxify the blood adequately then toxins will come out through the skin causing irritation and blemishes, rashes or acne. Rosacea is a bit more complex but I have had success using a tea called ESSIAC. It is classically used for the treatment of cancers. This tea does so my gently, but powerfully cleansing the liver. The nice thing about this tea (I recommend brewing it yourself rather than taking the capsules or tincture) is it is very safe and I even give it to teens with acne issues.
Western Botanicals makes this and it is about 1/4 of the price of the canadian company who owns the name. The recipe was leaked out about 20 years ago and now many companies make the formula.
Of course, the standard recommendations hold true as well, avoid direct sunlight, etc.
Hope this helps
herbdoc