If you write it in the next paragraph (inscription), the words in the banner inscription should not be too many, especially in the text, such as four words, five words and six words. If there are many words in the text, the signature can be more words, but not more.
Suggestion:
So-and-so friend (or good brother, close friend, etc. ) belongs to Shu Ya (or "entrustment" is acceptable) Geng Yinchun's so-and-so letter.