Mark Quinn has lent money to about 50 small Bay Area companies, helping buy a dough roller for a Pinole bakery and a sewing machine for a Mexican immigrant’s embroidery business, for instance. […] the loans aren’t through his day job as San Francisco district director for the Small Business Administration. The enterprises and their loan sizes are too small for that agency or for bank financing, and the borrowers may not have qualified anyway. […] Quinn made personal loans through Kiva.org, a nonprofit that handles microlending — lots of people chipping in small sums that will be repaid. Microlending caught fire in the developing world, helping farmers buy goats, craftswomen procure supplies and villages dig wells. […] Kiva, which has a long-established lending program overseas, is launching an ambitious plan to promote microlending in the Bay Area, hoping to create a model to expand nationwide. The starter loans are $5,000 or $10,000, but eventually borrowers with good repayment histories can apply for larger amounts. Kiva hopes that its borrowers’ repayment histories can get reported to credit bureaus, allowing them to tap into traditional loans over time. In the U.S., Kiva started off using “trustees” — organizations like nonprofits, churches, community centers and veterans groups — to vouch for borrowers. Kiva is hiring dedicated staff for San Francisco and Oakland to recruit borrowers and lenders, and just kicked off an ad campaign on Muni buses and bus shelters.