I recently needed to only show the first three items of my repeater array. See below for an example of how to do so.
Set a variable $i as 0 outside the loop. Within the while loop have i count up by one and when it reaches the number of array items you’d like to display (in my case 3.) Then have it break.
<?php if( have_rows('annualreports') ): ?>
<?php $i = 0; ?>
<ul class="reports_list">
<?php while ( have_rows('annualreports') ) : the_row();?>
<?php $i++; ?>
<?php if( $i > 3 ): ?>
<?php break; ?>
<?php endif; ?>
<li><a href="<?php the_sub_field('annual_report_file')?>" target="_blank"><?php the_sub_field('annual_report_name');?></a></li>
<?php endwhile; ?>
</ul>
<?php endif; ?>
