The Lone Ranger, brought up a good example, I think should be pointed out. If you see someone/others not posting, take the initiative and post something like dialogue or something, that will get others involved. It's important that this RP has character development, so post something like dialogue that will get others involved. The downfall of most RP's is that people don't see others posting, and instead of taking the problem on themselves with a simple post, they pass the buck, and think someone else (who's also thinking to pass the buck), will take the responsibility. And from there it just goes over and over again. We don't want that, especially with how early on we are, so take the initiative and if people aren't posting, then do so yourself, even if you think hogging or you're posting too much.
In my RP's there is no such thing as posting too much, because character development between characters is important here.