Arrange the stitches so that all of the instep stitches are on one needle and all of the bottom of the foot stitches are on the other needle.

Cut your yarn, leaving a long tail (about 3-4 times longer than the width of the fabric to be grafted). 

Thread the end of your yarn on a tapestry needle.

Hold the project so that one needle is in front and one behind with the needle tips pointed to the right.

Set up for working Kitchener stitch:

First, insert needle as if to purl in the first stitch of the front needle and draw through.

Next, insert needle as if to knit in the first stitch of the back needle and draw through.

Now that the set-up is complete, follow these steps to graft:

1. Insert needle as if to knit in the first stitch of the front needle.

Slip that stitch off the needle and draw yarn through without pulling too tightly.

2. Insert needle as if to purl in the next stitch of the front needle and draw through, leaving this stitch on the needle.

3. Insert needle as if to purl in the first stitch of the back needle.

Slip that stich off the needle and draw yarn through without pulling too tightly.

4. Insert needle as if to knit in the next stitch of the back needle and draw through, leaving this stitch on the needle.

Repeat steps 1-4 until only 1 stitch remains on each needle. Then simply slip the needles out.

I have a chant that always helps me maintain a good rhythm while working Kitchener stitch:
"As if to knit, slip off; as if to purl, leave on. As if to purl, slip off; as if to knit, leave on."

I just repeat that mantra as I work and it helps keep me from getting confused.

And there's your sock toe!

When you finish, you may notice that the grafted stitches aren't quite the same gauge as the surrounding stitches. Just use your tapestry needle to gently tug on the stitches, one at a time until they are more uniform. 

If you have any gaps on either side of the graft, use your remaining tail to cinch them closed while you weave it in.