Hi blueguy,
That depends on whether the images are 'in-line' or not.
With 'in-line' images, you can only select one at a time. Once you've
re-sized one, though, selecting each of the others in turn and pressing F4
will repeat the re-sizing action on them too.
With other images (eg formatted as 'square', 'tight', etc) you can select
more than one at a time by selecting the first image then holding down the
Shift key as you click on each additional image.
To see whether an image is 'in-line' or not, select it and use
Format|Picture|Layout. Alternatively, simply try selecting it and another
image - if doing so selects both the images and any surrounding text, at
least one of them is 'in-line'.
Cheers