[oXygen-user] external tool to run a bash script

I'm sure I'm doing something stupid, but ... I have a bash script (I'm on Mac OS X 10.8.5) that calls Jing with the simplify option to turn a modular Relax NG compact schema into a simplified monolithic RNG for further processing. It runs just fine from the command line, but I have been trying to implement it as an external tool. The command I use for the external tool is source /Users/taraathan/SimpleApps/oxygen/simplify-rnc2rng.sh ${cf} ${cfd}/tmp/simp-${cfne}.rng with working directory /Users/taraathan I get the error message Could not start: Cannot run program "source" (in directory "/Users/taraathan"): error=2, No such file or directory Process ended with exit code: -1234567 Any suggestions? Thanks, Tara