You can download all RefSeq proteins for B. subitlis str 168 by visting this page:
and then clicking on the 'Project Data' icon on the top right corner of the page. Afterwards, you could run them through some of the programs that were suggested by Varsha to see which ones are predicted to be secreted. Check out the bioinformatics section of this paper for ideas: http://genomebiology.com/2008/9/2/R35
However, at the end of the day, bioinformatic predictions are one thing, but eventually, you'll need some lab validation experiments...