The ALMA Proposal Template (available for download from the ALMA Science Portal) is a LaTeX file that is pre-formatted for A4 letter format. Further, it has the all-caps instruction "DO NOT CHANGE" on the section that sets the page dimensions. So users should not change the latex so that it formats to US letter. Instead, create the PDF file and have it print out in the format you want, using the following commands:

prompt>latex My_ALMA_Proposal.tex

This should produce a .dvi file (e.g. My_ALMA_Proposal.dvi), which can be converted to a letter formatted postscipt file:

prompt>dvips -t letter My_ALMA_Proposal.dvi

The resulting .ps file should be properly formatted to letter format and can be sent to a letter format printer.