Hi kankon,

Set dir="rtl" to menu DIV in master page.

If you want complete form to be right to left set it in form tag.

MasterPage

<form id="form1" runat="server">
    <link rel="stylesheet" href='http://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.0.3/css/bootstrap.min.css'
        media="screen" />
    <script type="text/javascript" src='http://ajax.aspnetcdn.com/ajax/jQuery/jquery-1.8.3.min.js'></script>
    <script type="text/javascript" src='http://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.0.3/js/bootstrap.min.js'></script>
    <div class="navbar navbar-default">
        <div class="container-fluid">
            <div class="navbar-header">
                <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#bs-example-navbar-collapse-1"
                    aria-expanded="false">
                    <span class="sr-only">Toggle navigation</span> <span class="icon-bar"></span><span
                        class="icon-bar"></span><span class="icon-bar"></span>
                </button>
                <a class="navbar-brand" href="#">ASPSnippets</a>
            </div>
            <div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1" dir="rtl" style="text-align: right;">
                <asp:Menu ID="Menu1" runat="server" Orientation="Horizontal" RenderingMode="List"
                    IncludeStyleBlock="false" StaticMenuStyle-CssClass="nav navbar-nav" DynamicMenuStyle-CssClass="dropdown-menu">
                </asp:Menu>
            </div>
        </div>
    </div>
    <script type="text/javascript">
        //Disable the default MouseOver functionality of ASP.Net Menu control.
        Sys.WebForms.Menu._elementObjectMapper.getMappedObject = function () {
            return false;
        };
        $(function () {
            //Remove the style attributes.
            $(".navbar-nav li, .navbar-nav a, .navbar-nav ul").removeAttr('style');

            //Apply the Bootstrap class to the SubMenu.
            $(".dropdown-menu").closest("li").removeClass().addClass("dropdown-toggle");

            //Apply the Bootstrap properties to the SubMenu.
            $(".dropdown-toggle").find("a").eq(0).attr("data-toggle", "dropdown").attr("aria-haspopup", "true").attr("aria-expanded", "false").append("<span class='caret'></span>");

            //Apply the Bootstrap "active" class to the selected Menu item.
            $("a.selected").closest("li").addClass("active");
            $("a.selected").closest(".dropdown-toggle").addClass("active");
        });
    </script>
    <hr />
    <asp:ContentPlaceHolder ID="ContentPlaceHolder1" runat="server">
    </asp:ContentPlaceHolder>
</form>