Rinse and wash the rice well. Then soak the rice in enough water for minimum 2 hours. 

Drain the water completely and keep it in the colander for about 10 minutes. This lets the remaining water to completely drain. 

Then spread it in a clean cloth or something that absorbs the moisture. Keep it at the counter for about 20 minutes (refer notes). 

Once the rice is slightly dried (if you touch the rice it should be damp but not wet), transfer it to a mixie (the indian blender) or a high power blender. Grind it for about 1 or 2 minutes max. If the mixie heats up, wait and then grind.

Sieve and transfer the grits back to the mixie. Now along with this add the next batch of rice and do the same process. Repeat until all the rice is ground and you have a fine rice flour.

Please note that the rice flour ground at home will not be smooth, not powdery smooth. It will slightly be grainy. Note, just slightly. 

If you are not using the flour right away, let it air dry overnight and store it in an airtight container. The shelf life is few weeks depending on the climate. If its humid and warm, fungi will form soon. So store it in a refrigerator. 

You can also roast the flour in a pan until it becomes warm to touch. Let it cool completely and then store it in an air tight container at room temperature. This will extend the shelf life. 

In either of the methods, home made rice flour will not stay good for a longer period. Finish it soon.