To support synchronization between Source and Preview windows, and error location in projects, the TeX Command Line Preferences set in TeXShop Preferences under the Engine tab should contain the following flags:

1. The pdftex preference should be
     pdftex --file-line-error --synctex=1
2. The pdflatex preference should be
     pdflatex --file-line-error --synctex=1
3. The TeX + dvips + distiller preference for TeX should be
     simpdftex etex --maxpfb --extratexopts "-file-line-error -synctex=1"
4. The TeX + dvips + distiller preference for LaTeX should be
     simpdftex latex --maxpfb --extratexopts "-file-line-error -synctex=1"

How do I configure TeXShop?
TeX Command Line Preferences