change number of result via siapi

use this

public void setRequestedResultRange(int fromResult, int numberOfResult) throws SiapiException

Sets the rank (ordinal position) of the first result required for this query. Result ranks start at 0. For example, having first-result 17 and num-requested-results 4 will retrieve 4 results, those that were ranked 17 to 20. The parameter values may have implementation dependant restrictions.