Use the rename function, to rename your fields with spaces to fields without spaces:
... | rename "Total Replies" AS TotalReplies, "Rating Score" AS RatingScore
Then apply your eval (may I suggest you don't use a space in the name of your field in the eval?):
... | eval RatingCalculation = TotalReplies * RatingScore
Once all this is done, you can then rename them back to having the space between words. But I would leave this rename to the very last step in your search, to avoid further issues with fields with spaces:
... | rename Rating* AS "Rating *", TotalReplies AS "Total Replies"
Your full search would look like this:
<your base search> | rename "Total Replies" AS TotalReplies, "Rating Score" AS RatingScore | eval RatingCalculation = TotalReplies * RatingScore | rename Rating* AS "Rating *", TotalReplies AS "Total Replies"
Hope this helps
