One of the best ways to get other people to try out your game is to offer to play THEIR games and then offer detailed, constructive feedback and bug reports (My party got stuck at the bridge in Gotham for example). It doesn't mean you need to play through their entire game if you don't have a lot of free time. Sometimes even 15 minutes of playtesting can be a huge help.
Also, when people offer you feedback, it's very important to take it seriously and fix what's not working in your game. Otherwise, why bother asking for feedback, if you're not going to fix what people find? When I got some feedback on my IGMC game, I immediately addressed it, even though some of the problems required a fair bit of work on my part (changing floor tile types for example), and the result was a much improved game.
Beyond that I agree with what everyone else has said --- if you're an actively participating member of the RPG Maker community, you're a lot more likely to get people who will reciprocate and test out your game a bit.
On the bright side, it is a very active user community, so you actually CAN get noticed by other community members. It does just take time.
Finally, when you make a game, even if you're not selling it, make sure you do your best to fix bugs and glitches before even asking people to playtest it. If I offered to playtest someone's game, especially if they said it was Completed, and it was very buggy, I'd give them the bug reports and not play any more of their games, because I'd assume they couldn't be bothered to test their game before releasing it.
I'd expect early builds to have bugs, but even then I'd spend at least a day bugfixing before asking others to use their limited free time to playtest my game. Remember, people's free time is at least as precious a resource as money, treat it with respect.