CatatanRevolusi - It’s just simple. In Blogsome, you must first deactivate the WYSI Wordpress Plugin. Plugin-> click deactivate on WYSI Wordpress Plugin. Then for every post click Quicktags "more", where the text cut off.
If you want to change all of your post with this "read more", just go to Manage->File, then click Post File and edit them.

Replace this one {the_content} or {content}

with {the_content more_link_text="Read more… (YOUR TEXT HERE)"}

Or if you don’t want deactivate the plugin, you can just insert this code  <!—more—> in html format on your post.

Enjoy it!