I have been using WPS Office for quite some time now, and I am really not looking back. The default spellcheck that comes with the office is American English (en_US). I wanted to add a spell check in Writer for British English, since this is what I normally use for documents.
So, I found dictionaries at the Downloads section of the WPS Community page. The one I need is en_GB.zip. I placed the unzipped folder in
~/.kingsoft/office6/dicts/ and then opened Writer and went to:
Options > Spell Check > Custom Dictionaries > Add
Then I navigated to the dictionary file
~/.kingsoft/office6/dicts/en_GB/main.dic and then selected the new dictionary: