Hello,
Unfortunately, there is no such possibility. I would recommend you to add the text manually on the slider, as on our demos. The size of the button can be changed via custom CSS code –
.slide-button {
padding: 8px 15px !important;
font-size: 11px !important;
}
http://prntscr.com/pf67sh
Also, you can use the Slider Revolution plugin, it has more settings but can slow down the site a bit.
Regards