Letter

All the default templates in Synapse are in A4 format.  If you wish to use Letter paper instead ( Letter paper is standard in the USA, and A4 the rest of the world ), then you need to change the template type from A4 to Letter.

So, at the top of each template is a line like this

pagesize A4

and you would change that to

pagesize Letter

But there is more to do.  Because A4 is 50 points longer than Letter paper, if you just change the paper type, everything will be too high on the page ( because the paper is now shorter, and the 0x0 point is at the bottom left in PostScript. ) So, you would have to change all the coordinates by reducing the Y values by 50. 

Versions later than R213B40.4 now have a button that will do the conversion for you.  It will change A4 to Letter, and back again.  Give it a go, and report any problems.  It's found on the Postscript templates page under the actual template.