Turn over the rug and lay it on the carpet.
How to get rugs to lay flat on carpet.
Many times this will allow the rug to lay smooth for a while.
Take a wet towel and moisten the areas where the carpet is curling.
With the towel still covering the carpeted area hold down the iron and press.
However for rugs that are nowhere near furniture in the center of a hallway or foyer for example the carpet to carpet non slip pad is your best option for preventing ripples in your area rug.
If the ends still curl up move to the next steps.
Turn over the rug with the right side down.
Apply carpet tape around the edges of the rug.
Cut tape to fit each edge of the rug.
This should flatten the areas out.
Then take an iron and set it to a medium heat.
Apply the tape to the edges of rug.