If you want to spread landscape fabric on the base of a raised vegetable bed, break up the soil at the base of the bed with a garden fork and lay the fabric on top. Then you can fill the bed with a soil and compost or manure mixture for growing your plants.
There is a simple technique to follow to plant vegetables with landscape fabric. Prepare the soil of the vegetable garden, applying fertilizer or compost if desired. Partially unroll the end of the landscape fabric parallel to any side of the garden. Secure the end with rocks, bricks, soil or landscape anchor pins.