<select name="data[Post][project_id]" style="width:100%;" class="form-control selectpicker" id="project" title="Projects" data-live-search="true" data-width="100%">
    <option value="">Project</option>
    <option value="1">Project 1</option>
    <option value="2">Project 2</option>
</select>

<script>
    $(document).ready(function () {
        $('.selectpicker').selectpicker();
    });
</script>