How to Find Relevant forum- SEO tips

some of the footprints I use would be :

“powered by vbulletin” "Your Keyword"
“powered by yabb” "Your Keyword"
“powered by ip.board” "Your Keyword"
“powered by phpbb” "Your Keyword"
“powered by phpbb3″ "Your Keyword"
“powered by invision power board” "Your Keyword"

“powered by e-blah forum software” "Your Keyword"
“powered by xmb” "Your Keyword"
“powered by: fudforum” "Your Keyword"
“powered by fluxbb” "Your Keyword"
“powered by forum software minibb” "Your Keyword"
“this forum is powered by phorum” "Your Keyword"
“powered by punbb” "Your Keyword"
“powered by quicksilver forums” "Your Keyword"
“powered by seo-board” "Your Keyword"
“powered by smf” "Your Keyword"
“powered by ubb.threads” "Your Keyword"
“powered by the unclassified newsboard” "Your Keyword"
“powered by usebb forum software” "Your Keyword"
“powered by xennobb” "Your Keyword"
“powered by yaf” "Your Keyword"
“Powered By MyBB” "Your Keyword"
“Powered by IP.Board” "Your Keyword"
powered by phpbb "Your Keyword"

this should get you started 

there are many more terms to use also but this should be a great start


clarification above:

Replace the "Your Keywords" or "KEYWORDS" with Your desired keyword.

Let you are interested to find out forum which content is food related

So,

“powered by vbulletin” "Your Keyword"

“powered by vbulletin” "food"

Here Keywords are Replace by food 

Take care gyz...