CHILD PAGES of the current page in POST format LIMIT each

I have some empty parent pages. Each parent page has child pages. When I click on parent page I see all child pages in post format. To do so, I used this code.

All I need now is to limit each child page (in post format) with “read more” link. Are there any solutions?

I tried “WP Limit Posts Automatically” plugin, but it acts only on posts, not pages.

Please help ??
Thanks