On the Database tab there dropdown in the lower portion of the panel for Full Text OCR Field. Put the name of the field that will store the full-text data there. This must be configured both for Insert and Retrieval mode configurations. The database field needs to be sufficient length to store the entire text of your document.
Of course, the Insert Mode configuration must have “Enable Full Page OCR” checked to generate full text data from images. Text from MS Office documents, PDF files and existing OCR text files can be used without setting this option.
When designing your Retrieval Mode configuration, create a Text field to use for full text search queries. On the Database tab, set the corresponding “Database Field Name” to the full text database field.
When searching on your full text field, SimpleIndex finds the text you enter no matter where it appears in the document. It is able to match partial words. It does not perform boolean or natural language searches. The text entered must match the document text exactly.