I use a script to set the svn:keywords properties recursively for all files of a given pattern:

#!/bin/sh
PATTERNS="*.txt *.java build.xml *.properties *.sh *.sample"
KEYWORDS="Date Id Rev Author"

for PATTERN in $PATTERNS
do
    find . -name "$PATTERN" -prune -exec svn propset svn:keywords "$KEYWORDS" \{\} \;
    echo "-----------------"
done

echo
echo "don't forget to execute 'svn commit'."

Modify the PATTERNS and KEYWORDS variables as you like, and execute it with

./setSvnKeywordProperties.sh .

to set properties for all the files found by the script. You can do a

svn st

to list all files that are modified with this action, and commit via

svn commit