Browsersync + Jekyll + PHP Server

I have vagrant witch scotch box, ip: 192.168.33.10

In public dir I have jekyll under jekyll dir ../public/jekyll files are generating to

../public/jekyll/_site

How to run browsersync with proxy to this server (192.168.33.10) and serve files from jekyll/_site ?

my current gulp task for browsersync is:

gulp.task('browser-sync', ['jekyll-build'], function () {
    browserSync({
        server: {
            baseDir: '_site'
        },
        open: false
    });
});

I try to set proxy to 192.168.33.10 but it links only to main dir on vagrant (public) not inside jekyll/_site. I cannot set baseDir with proxy at the same time