Boostrap 4 Navbar Collapse Menu Right Align

Just use "text-right" in HTML

For example:

<div class="navbar-collapse text-right" id="navbarResponsive">

Just add simple rule to your css.

 .nav-item{
    text-align: right;
}

According to http://getbootstrap.com/docs/4.0/components/navs/#horizontal-alignment, the way to center, right-justify, or left-justify things in the navbar's collapsed dropdown is to use justify-content-end and friends in the class of a nav.

Example. This code yields the image following it.

<nav class="navbar navbar-expand-lg fixed-top">
    <div class="container">
        <!-- Brand and toggle get grouped for better mobile display -->
        <ul class="list-inline social-buttons">
            {% for link in site.social %}
            <li class="list-inline-item">
                <a href="{{ link.url }}"><i class="{{ link.icon }}"></i></a>
            </li>
            {% endfor %}
        </ul>

        <div class="navbar-toggler" data-toggle="collapse" data-target="#menu">
            &#9776;<!-- three bars symbol -->
        </div>

        <!-- Collect the nav links, forms, and other content for toggling -->
        <div class="collapse navbar-collapse" id="menu">
            <ul class="nav ml-auto">
                <a class="nav-link page-scroll" href="#about">About</a>
                <a class="nav-link page-scroll" href="#projects">Projects</a>
                <a class="nav-link page-scroll" href="#writing">Writing</a>
                <a class="nav-link page-scroll" href="#contact">Contact</a>
            </ul>
        </div>
    </div>
</nav>

Now amending that one line to:

<div class="nav ml-auto justify-content-end">

yields

Note this evidently has nothing to do with ml-auto, which when missing causes the uncollapsed menu items (on a wider screen) to not be right-justified. (The toggler button itself is always right justified for me.) Only justify seems to control the stuff in the uncollapsed menu.