Feature Images and Read More

<!-------------------------------------------Theme Feature images support and cropping  and read more link----------------------------- >
add_theme_support( 'post-thumbnails', array( 'post' ) );
add_image_size( 'post', 191, 191, true );/*croping */
<!--------------------------------------------------------Read More-------------------------------------------------->
/*code for read more link*/
function excerpt($num) {
		$limit = $num+1;
		$excerpt = explode(' ', get_the_excerpt(), $limit);
		array_pop($excerpt);
		$excerpt = implode(" ",$excerpt)." <a href='" .get_permalink($post->ID) ." ' class='".readmore."'>Read More</a>";
		echo $excerpt;
    }
<----------------------------------------Active Read More,actually where need read more past blew code--------------------------------->
/*active read more function in our location*/
<?php echo excerpt('15'); ?>/*here 15 means after how many words we get read more link*/