In short: KildClient uses the same dictionaries that other software your distribution uses, so if you can spell check in LibreOffice, Firefox, etc, KildClient should be able to spell check.
More specifically, KildClient uses the enchant library for spell checking. enchant allows several dictionary backends to be used, such as aspell, myspell, hunspell, etc. That is the same library LibreOffice and Firefox use, among others. Look in you distribution package list for spell checking dictionaries (generally named myspell-<language> or something similar) and KildClient should detect and use them. Since the exact procedure varies from distribution to distribution, please consult your distribution documentation for more information.
Windows
KildClient version 3.0.0 and up uses dictionaries in the same format as LibreOffice. The procedure for installing dictionaries is, unfortunately, somewhat involved, as there isn't a repository for the dictionaries. To install dictionaries and enable on the fly spell checking, follow these steps:
- Download the LibreOffice extension containing the dictionary for the language you want from the extensions repository.
- The downloaded file is a Zip archive, just with a different extension. Rename the downloaded file changing the .oxt extension to .zip, and open it.
- Inside, locate two files with .aff and .dic extensions. There should be two files with the same name and these two extensions. Depending on the package you have downloaded, there might be other files (such as hyphenation support files) with similar names. Those are not used by KildClient.
- Copy the .aff and .dic files to the %LocalAppData%\enchant\hunspell folder. If this is the first dictionary you are installing, you will need to create the two folders. (%LocalAppData% is and C:\Users\<username>\AppData\Local. You can use %LocalAppData% in Explorer, it will open the correct folder.)
- KildClient should now be able to use the dictionaries.