I do not have this option on my last title that is in KDP Select. However, I know where the Amazon ad network lives if I wanted to go buy CPC ads for my book. My issue is why am I going to pay a company that already takes a 30% cut of my product's sale additional monies to advertise my book on their site? Something is fundamentally wrong with that system. I think I will stick with my plans of building my own following. 