Latexian Help > Selecting a Typesetter
The Preview and Export functionality in Latexian requires that you have the MacTeX or BasicTeX (2009 or later) distribution installed. Both of these can be downloaded from the MacTeX website.

Latexian has support for three typesetters: LaTeX, LaTeX (DVI), and XeTeX. Which one is used depends on the File Type settings for the document that is being processed. If you want to select a typesetter on a per-document basis (perhaps, you have both LaTeX and XeTeX documents that use the same file extension), then you can specify a typesetter in the Get Info panel. With the document open, select "Get Info" from the "File" menu. If the File Type for the document is set to LaTeX or XeTeX, then the panel will include a drop down list labeled "Typesetter", where you can specify the typesetter to use for that document only.

By default, Latexian looks for the pdflatex, latex, or xelatex executable in the /usr/texbin directory. If you have MacTex installed in a different location, you can specify the location in the Preview section of Latexian's Preferences.