do you have a SITD foot? it has the bar down the center,a little easier to follow! then your needle can be even with it, or to the right of left of the bar, but the bar will ride the seam or ditch..
i have heard from different people that in the ditch, is right on the seam..others say it is actually just left or right of the the "ditch" or seam.
http://quilterpenny.wordpress.com/20...-in-the-ditch/