Question

How to limit the number of pages to process?

Answer

The main idea for such a scenario is to use the Recognize method of the FRPage object for each page you need.

CheckResult( frDocument->Preprocess( 0 ) );
CheckResult(frDocument->Analyze());
for (int i = 0; i < 10; i++) {
    CheckResult(frDocument->get_Pages(&frPages));
    CheckResult(frPages->get_Element(i, &frPage));
    CheckResult(frPage->Recognize());
}
CheckResult(frDocument->Synthesize());

The code above will recognize only the first ten pages in the document.