Doctor recommended rice for babys bottles?

My baby recently has started throwing up almost everytime she eats like projectile everywhere. So I took her to her pediatrician today & he said to start adding rice to her baby bottles, to thicken it so she doesn’t throw it back up. But isn’t rice a chocking hazard? She’s only 7 weeks old. When I questioned it he said the rice in bottles helps reflux babys keep food down.