Supplies : yellow flocking or yellow paint,toothpick
At this point you can either add a tiny accent of yellow flocking to the bottom petals, or paint a tiny accent on them with yellow paint. I personally prefer seeing the texture of the flocking. I had to purchase flocking on amazon, I bought a set of 10 or 12 colors, it comes in really handy for flower making. Or look in the rail road supply section, they sell a marigold colored flocking that's used for ground cover.
So, if you're using the flocking the first step is to add a speck of tacky glue for the flocking to stock to. This would go just at the top of the bottom petal in a little stripe.