use Net::SFTP::Foreign;
use Fcntl qw(SEEK_END);

my $host = ...;
my $file = ...;

my $sftp = Net::SFTP::Foreign->new($host);
$sftp->error and die "Unable to connect to remote host: ".$sftp->error."\n";

my $fh = $sftp->open($file)
    or die "Unable to open file $file: ".$sftp->error."\n";

# go to end of file
seek($fh, 0, SEEK_END);

my $sleep = 1;
while (1) {
    while (<$fh>) {
        print;
        $sleep = 1;
    }
    sleep $sleep;
    $sleep++ unless $sleep > 5;
}