As someone who always used to eat rice with a spoon, the first time I moved to the US for studies and saw people eating rice with a fork, I couldn't stand it.
I tried it myself, but damn it - trying to balance the rice grains, without having them fall through the forks was annoying.
At first, I would ask for a spoon. This raised some eyebrows, but nothing more (this was in Texas, if that matters). This lasted for about a week; and eventually I got tired of asking for spoons because each time they would bring me a spoon, it would be a large (to me) spoon, so either they had the very tiny dessert spoons, or the large soup spoons. I was used to a more normal "eating" spoon.
Eventually I got used to eating rice with a fork ... and when I came home and went hunting for a fork to eat rice, my mom gave me a look like what is wrong with my son. This is because in our household - forks are reserved for desserts (mainly, cakes), and sweets. Not for (as my mom would say) "eating".
The bottom line from my personal experience is - use what makes you comfortable eating (like my friend that used to eat pizza with a knife and fork, as if it was some steak). A few people may simply look up once, and then go back to their own food.
It is most definitely not rude by any stretch of the imagination (although some passionate pizza lovers did make some comments - but all in jest).