Any users installing Write-N-Cite on a Mac, first need to download and install a free compression/archive tool called "Stuffit Expander". (similar to WinZip for the PC) Without this tool the user cannot uncompress the Write-N-Cite download, and therefore cannot begin the installation process.
Staff from RefWorks, told us:
Write-N-Cite for the Mac needs to be "unstuffed" using a software called Stuffit
Expander. Stuffit Expander used to come pre-loaded on Macs, but apparently
with the latest Macs, it no longer is on there. Stuffit Expander can be
downloaded for free ( http://www.stuffit.com/mac/expander/ ).