A lot of people on the board use either a block of Post-Its or Command Strips positioned on their footplate to give an exact 1/4" or scant 1/4" and then simply run their fabric against the block - voilą - perfect seams!
Not sure if you have Command Strips - they're not very common here, but Staples carries them as do some DIY chains. Even with postage, you'd probably be cheaper from eBay US. The good thing about them is that they're removable and won't damage your machine.