To insert a file immediately after the line containing the cursor:
:r examples.txt
This inserts the contents of the file examples.txt immediately after the current line.
To insert the contents of another file after a specific line in the current file:
23:r toc.txt
This inserts the contents of the file toc.txt after line 23 of the current file. Line 24 is empty; the contents of the inserted file begin at line 25.