jQuery Grid Plugin - jqGrid

Please let me know how do I pass the rowid to the adddocmultim function in the following code. rowid will be the row id of the selected row in the grid.

$grid->setNavOptions('navigator',array('add'=>false,'edit'=>false,'del'=>false));
$buttonoptions = array("#docpager2",
    array("buttonicon"=>"ui-icon-plus","caption"=>"","position"=>"first","title"=>"Add Documents.", "onClickButton"=>"js: function(){adddocmultim("+rowid+";}")
);
$grid->callGridMethod("#doclist2", "navButtonAdd", $buttonoptions);

Many thanks.