You can urinate in a composting toilet if you want too but if you're in a rural area and are using a composting toilet instead of a flush toilet you can use your urine to actually fertilize plants with.
Instead of urinating in the composting toilet urinate into a jug or bucket and then use the urine to deep root fertilize plants or you can also just urinate outside on the ground directly anywhere you want too in if you're in the countryside.
That's one good thing about being out in the countryside as if you need to urinate you can just pee anywhere you can without having to run to the toilet.