How to import rules on site install?
Assuming this is for D7, try this code (which includes a copy of your exported rule):

function my_module_default_rules_configuration() {
  $configs = array();
  $rule = '{ "rules_vote_points" : {
      "LABEL" : "Vote points",
      "PLUGIN" : "reaction rule",
      "REQUIRES" : [ "userpoints_rules", "voting_rules" ],
      "ON" : [ "voting_rules_insert_node" ],
      "DO" : [
        { "userpoints_action_grant_points" : {
            "user" : [ "node:author" ],
            "points" : "3",
            "tid" : "0",
            "entity" : [ "node" ],
            "operation" : "Insert",
            "display" : 1,
            "moderate" : "approved"
          }
        }
      ]
    }
  }';
  $configs['rules_vote_points'] = entity_import('rules_config', $rule);
  return $configs;
}


PS: have a look at the code of the Answers Userpoints module for an example where this technique is used also (contained in answers_userpoints.rules_defaults.inc).