I'd go with Bryant's suggestion - use a weed eater then lay your fabric. I normally lay the fabric over the grass and use a number of staples to hold the fabric down.
The fabric will kill anything you lay it on top of. The issue is wind getting under it and "removing" it. Small squares in your yard are no problem. But longer runs the danger goes up.
Remember these picture anyone?
That was a bad day to be in the nursery business! We had put down 15' wide X-cell fabric covering about 125 x 200 (if memory serves).
The smoother the surface underneath is the less chance there is for the wind to get ahold of it. And will reduce the number of stakes and rock. Another trick is to dig a trench around the edge and back fill on to the fiber.