Hi,
I'm not an expert but I don't think force to rate your app is a good idea.
It's better if you explain to the user that it's important to support your app.
In my game when the user complete the puzzle I ask if he could support my app giving a rate and I have a button for that.
Check the last screenshot here:
https://play.google.com/store/apps/details?id=it.megasoft78.fifteenpuzzlex