Change the sidebar from left to right twentyfourteen theme

Old post, yet its needed to know the solution and how-to.
Specially for RTL experience,

Usefull tutorial here

As @Mayeenul Said, first create a child theme (Video)

Then add to your CSS file in child theme the following:

.sidebar {
        float: right; // the side bar will be on right
        margin-left: -100%;
        max-width: 413px;
        position: relative;
        width: 29.4118%;
    }
.main {
        display: block;
        float: left; //the content will be on left
        margin-right: 29.4118%;
        width: 70.5882%;
    }

Please note that you might need to change the sidebar’s and main’s selector based on your working theme, ie. .sidebar could be #theme-sidebar and .main could be #theme-main, etc.