The ready-to-feed usually is a bit thicker. Maybe you can make up your bottles and allow them to sit overnight to thicken. Also, the RTF actually tastes different (I was shocked to learn that there are actually different ingredients between powder and RTF for some brands... :shock: ).
It may help if you make a gradual transition. Like for a week or so, do a 75/25 bottle (liquid to powder), and gradually wean off the liquid.
Good luck! :wink: