Dutch speaking people can stress their syllables by adding an acute accent to it. So, ‘ík’ is ‘ik’ with extra emphasis. There is one special case: the ij. Both the i and the j should get an accent. There is no j with an acute though.
Even though practically non-existent in prescriptive German orthography, the lowercase sharp s (ß) has been used more often between capital letters in recent years. Here’s how to implement it in your font.