What is proper, an RP or a RP? In reference to the grammar of the word roleplay, what do you use? English

"a" because it's in front of a constant sound

I'm going with an because though R is a consonant, the sound is a vowel. Which goes to show you how hopeless it can be to ask the internet.

It needs to agree with the vowel sound, not just the vowel, so "an hour" is the correct way.

an because the R has a vowel sound.

yep, "an"

I use both depending on how I'm using it in a sentence.