When adding 'ar' to a word, tone change is required (kaau -> kau'ar), unless it is a flat tone. Here are some of the examples:
bø'ar '帽仔'
ban'ar '慢仔'
bang'ar '網仔'
bong'ar '墓仔'
biø'ar '廟仔'
chi'ar '市仔'
chim'ar '鐃仔' 
chiu'ar '樹仔'
chviu'ar '象仔'
hai'ar '害仔'
hang'ar '巷仔'
ho'ar '雨仔'
hoe'ar '會仔'
hu'ar '符仔'
ku'ar '舅仔'
lo'ar '路仔'
pe'ar '父仔'
phia'ar '癖仔'
phvai'ar '揹仔'
phvi'ar '鼻仔'
pong'ar '磅仔'
siu'ar '壽仔'
sun'ar '順仔'
tau'ar '痘仔', '豆仔'
te'ar '地仔'
ti'ar '弟仔'
te'ar '袋仔', '弟仔'
ui'ar '位仔'
viu'ar, '樣仔'
ze'ar '坐仔'
zu'ar '墊仔', '苴仔'
zun'ar '陣仔'