How to display total number of records in the OBI EE Report ?

Create a report with the required columns.
For example: 
1. I have taken PROD_ID, PROD_NAME, PROD_DESC, Count [ Rename PROD_ID column to Count] columns on the report editor.

Write the following expression in the Edit column properties of Count column.
MAX(RCOUNT(PRODUCT.PROD_ID))
It gives the total count of records in the report.
2. Hide the Count column using Edit column properties.

3. Create a Narrative View with the below text.
Total number of records in the report is [b]@4[/b].
Here @4 represents the 4th column values [ Count column]
Enter Rows to Display as 1.

Add Narrative view to Compund layout and view the results.