append end of line with 8 spaces

child_amt=$amount
prev_line="$prev_line $child_amt"

i am getting the result like this

21234567890001343 000001004OLFXXX029100020091112 0000060

but i want 8 spaces between the eg:

21234567890001343 000001004OLFXXX029100020091112          0000060

how can i do this in .ksh

try

prev_line="$prev_line        $child_amt"
# or
prev_line="$prev_line"'        '" $child_amt"
# or
printf "%s        %s"  $prev_line $child_amt | read nline
prev_line="$nline"