My publisher has made the books available through Amazon all over the world. So when I do promos, I make sure to include links for places like the UK, Canada, Australia, France, etc. I also try to engage with readers from other countries by hosting giveaways especially designed for International readers.
Besides that, I've made sure to list my books in different book sites from different countries. For example, I've uploaded my book covers, blurbs and buy links to a site called iAuthor which is for readers in the UK.