When development teams have people working on a variety of platforms, its pretty common to end up with wrong line endings. In vim these will look like ^M at the end of each line. To get rid of these line endings you can use the following command (in command mode)

:% s/^M$//

To type the correct ^M character, you'll need to press Ctrl + V followed by Ctrl + M (the first combination means "take the next combination literally).

To turn this into a macro you should do the following. In command mode, pressq, followed by any letter. This will be the shortcut to access the macro. Then type the command as above. Finally, press q again to stop recording and its done. You can use your macro by pressing @ and then the letter you chose.