To set the PHP script memory limit in an `.htaccess` file, you can use the `php_value` directive. Here's how you can do it:
1. Create or open the `.htaccess` file in the root directory of your website (or the directory where you want to set the memory limit).
2. Add the following line to set the memory limit:
```
php_value memory_limit 128M
```
In the above example, the memory limit is set to 128 megabytes (128M). You can adjust the value to suit your requirements. The value can be specified in megabytes (M) or gigabytes (G).
3. Save the `.htaccess` file.
Note: The `php_value` directive may not work if PHP is running in CGI mode or if you don't have the necessary permissions to override PHP configurations. In such cases, you might need to modify the `php.ini` file or consult your web hosting provider for assistance.