1. First, open the WPS application, log in or create an account. Find the document you want to sign, open it and find it.

2. Secondly, click the Insert option on the WPS application toolbar. On the Insert tab, find the Handwriting option, and then click Enter.

3. Finally, in the handwriting mode, you can use your finger or the stylus on your mobile phone for handwriting signature. After signing, click the Save button or Back button on the screen.