4d51ede8_rks_Search_UI_2_9___Lucidworks__Description
[Parameter] Use in "Find Similar" [Fields API Attribute Name] use_in_find_similar [Description] 
Controls whether this field is taken into consideration in find-similar/more-like-this computations. The field must be indexed for it to be used for find-similar. This setting can be changed without reindexing, as it is used at query time only.
Field Configuration - LucidWorks Search UI 2.9 - Lucidworks
Description