I have not been able to control the size of words from a count field (words have already been counted).
See https://observablehq.com/@pbrockmann/lsce_publications_keywords
A small example with the control of the size set from the number of occurence would be nice.
Thanks for the suggestion! I have just added the *fill* option to color the text depending on the word; it can also be a constant.
I've also sent a suggestion on your notebook to compute the sizes; the size function receives an array of words, so in your case you just have to take the Count property of the first (and only) element of the array.