Here's the work-around I posted to a similar question after weeks of frustration creating fillable/saveable medical forms with nearly a thousand entry fields
Short summary: To enable your respondents to circle choices, you don't have to do anything more than teach them to enable/display the oval drawing tool in Reader 9 and higher. You're already saving your forms as reader extended pdfs to allow people to save what they type, and this also enables the rich drawing functionality of Reader. Adobe has chosen to default reader to not show the drawing/typewriter tool bars, so in Reader 9.4 at least, you have to go to Tools > Customize Toolbars > every time you open reader.
Enjoy, I hope.