Bottle Nipples for Rice Cereal

Lindsay

I am planning to start adding rice cereal to my 6-month-old’s bottle. I am using Nuk Simply Natural Bottles. The nipples have either 3 holes or 9 but I don’t know if they’re fast or slow flow. Can I use either of those nipples with rice cereal? I was told to get “size 3” nipples but I cannot seem to find those for the bottles I have. Is anyone familiar enough with the Nuk Simply Natural bottles to offer advice? TIA!