It really doesn't matter. A lot of Westerners would use a spoon as well if they were given one. The spoon not being readily available at the table 100% of the time would be your biggest problem. But you should be able to ask the waiter/waitress for one. And apart from it looks somewhat odd no one would actually care. (unless you're at a really formal dinner with high placed individuals)

Not having a spoon shouldn't be a problem though. Burhan Khalid said rice would fall through the fork, but that's not true. The rice grains aren't small enough to fall through the openings in the fork, at worst they would get stuck in between. The real difference is that a fork is flat instead of cup shaped, so the rice falls off the sides when you take too much and you'd have to use a knife to square it up on the sides.

So give it a try, why not? But if you can't manage (like a lot of Westerners can't manage to eat with chopsticks) just use a spoon.