That's absolutely fine to do, just keep in mind that most people don't look through the actual Roleplay sections of the forum to find RPs to join, which is kind of the purpose of Interest Checks and their sections. You'll probably see decent activity if you put up a recruitment/advertisement thread in the Free Interest Checks section, even if it's just something along the lines of "hey, I'm opening a free for all type RP, here's the basic premise, come and join if you want."