Assuming svn keywords property is enabled on your office files you need add the keywords in the syntax shown below
Path of file in the subversion repository $HeadURL:: $
For the current $Revision:: $
For the checkin date $Date:: $
For Author $Author:: $
For the current $Revision:: $
For the checkin date $Date:: $
For Author $Author:: $
The noticeable difference from the keywords expansion in text file is the extra spaces given after :: if you don’t give extra spaces than your file will get corrupted as during expansion the space required for expansion will not be available and hence causing corruption of files.