i have 3 solutions for your request:

1.can use vfp browser IE (emulated as IE11) and automate it with a menu on a form to achieve that.
the browser works with designmode(.t. for edit mode or .f. for readonly normal mode)
can see a basic code at:
http://yousfi.over-blog.com/2016/01/internet-explorer-used-as-rich-editor.html
the menu (MPR) can be extended to another functions i dont updated that on this post.

2.can use an advanced editor as tinymce (it was free there was 2 years..to confirm).
can see that at (there is many codes how to work with):
http://yousfi.over-blog.com/2015/11/advanced-richtext-editor-tinymce.html

3.see also my richtext rtf editor at: http://yousfi.over-blog.com/2015/02/building-a-vfp-navigable-richtextbox.html

Good luck!

update:
-tinymce is shipped with a spellcheck
-in my IE11 the spellchecker dont appear at all in the menu "manage addons" .normally its here! i never use it also.